FR3037367A1 - ROTARY TURBOMACHINE ASSEMBLY WITH BOMB PROTECTED PADS - Google Patents

Abstract

The invention relates to a rotary turbomachine assembly, comprising a rotor disc (14), an upstream ferrule (48), a low pressure compressor drum (37), a plurality of blades (24) with platforms ( 28), and protective liners (50) each having two sidewalls each disposed between a blade root (26) and a tooth flank (18) of the disk (14) which it covers, and a transverse wall capping externally the peripheral tooth whose flanks are covered by said side walls. Rotating assembly both rotating and stopped, the transverse wall of each protective lining (50) has a volume shape to bear against a wall of one of the platforms (28), in order to press each platform against radially outer stops.

Description

The invention relates to a positioning of blade platforms 5 vis-à-vis the disk of a rotating turbomachine assembly, in particular a fan disk of a turbojet engine. double flow and double body. According to the known technique, and in this case, such a disc is connected to a shaft of the turbomachine, rotates about the axis of this shaft and has at its periphery a circumferential alternation of cavities, or grooves, and teeth of substantially axial orientations. The vanes extend radially from the disk into a fluid stream supplying the turbomachine. In a blower, the vanes extend radially in a vein up to the inner wall of an annular nacelle which externally defines this vein. The terms inner and outer are to be considered radially to the aforementioned axis of rotation of the turbomachine (longitudinal axis). In order to maintain them, the blades each have at their inner end a foot axially engaged in the grooves of the disc and retained radially by the teeth of the disc. A wedge is typically interposed between each blade root and the corresponding cell bottom, for purposes of maintaining, a priori prestressing, these elements. The blades are secured and retained upstream including an upstream cone connected to the disk. This cone forms the internal and upstream limit of the gas circulation vein of the turbomachine. As a reminder, a double-body turbojet engine typically comprises, upstream to downstream in the direction of flow of the gases, a fan in a casing, a double-body compressor, a combustion chamber, a double-body turbine and a jet nozzle. ejection. The two bodies, low pressure and high pressure, rotate independently of each other and are coaxial with the longitudinal (rotational) axis of the turbojet engine. 3037367 2 The fan is located upstream of the low pressure compressor which is followed by the high pressure compressor, and receives all the air flow entering the engine, inside a nacelle. More generally, it is conventional to provide, on a turbomachine, a rotary assembly comprising: a rotor disk having circumferentially an alternation of teeth and peripheral grooves, the grooves having flanks, a plurality of blades having feet mounted in the grooves, with inter-blade platforms mounted radially movable between radially outer and inner stops, respectively; - protective liners each having: - two side walls each disposed between a blade root and a tooth flank of the disc which it covers, and a transverse wall capping the peripheral tooth 15 whose sides are covered by said side walls. The above-mentioned protective linings are typically folded metal parts which protect, in particular when the turbomachine is running and the vanes are rotating: both the blade root surfaces and the disk which then come to bear strongly. against each other, and the surfaces respectively facing the inner and outer platforms of the teeth. Indeed, during the rotation of the rotor (rotating part of the turbomachine), the blades are subjected to centrifugal forces as well as axial aerodynamic forces. Under the effect of centrifugal forces, the blade roots come to abut against the parts (the aforementioned sides of the disc teeth) bordering the outer opening of the grooves. The surfaces of the blade roots and the disk abutting one another are commonly referred to as "spans". These spans are subjected to high pressure. As for the inter-blade platforms, their radially movable assemblies between the aforementioned radially outer and inner abutments bring them, when the rotor stops, to fall back against the outer surface of the peripheral teeth.

The "anti-wear" solution of the protective seals is useful in both cases. A problem remains however, relating in particular to the following: When the motor (the rotor) rotates, the platforms are pressed against the aforementioned radially outer abutments by the centrifugal force.

This ideally allows to create a perfect 3D vein between the different parts and avoids any risk of aerodynamic progress including rising. When the engine stops, the platforms are no longer pressed against these radially outer stops, so that when the engine starts again, these same platforms may not be re-plated correctly against all or part of said stops, which risks to generate the creation of aerodynamic markets, including rising. The 3D vein where the aforementioned blades extend will then be deformed, which could cause aerodynamic disturbances in the engine.

A proposed solution is that, in both rotating and stopping states of the rotary assembly above, the transverse wall of each protective lining bears against a wall of one of the platforms, by a volume form of this transverse wall, in order to press each platform against said radially outer stops.

In addition, it will be preferred that the peripheral teeth of the disc have surfaces which will form an inner stop for the inter-blade platforms, said surfaces being protected by the aforementioned protective linings, which will therefore cover them. Thus, it will limit the modification of the parts, thus avoiding significant costs such as the redefinition of parts that causes tool changes, for example.

A problem which is a corollary to the foregoing concerns the manner of obtaining this support effect between the platforms and these radially outer stops. Indeed, it is important that the effect is reproducible at each (re) start of the engine, this of course reliably and simply.

To this end, it is recommended that, to achieve said support, the transverse wall of each protective lining be convex radially outwardly. Thus, and even more so if each protective lining is an elastically deformable one-piece bent piece, as preferred, the spring-and-resilient effect of this bent wall will play effectively, under any circumstances. And for both ease of mass production and standardization of the stresses and reaction forces produced, it will be preferred that this convex transverse wall define an arc of a circle.

An alternative, or a complement, could be that, still to create said support, the transverse wall of each protective lining has substantially radial growths. This will increase the rigidity and increase the amplitude of the authorized radial movements of platforms, security pledges of 20 abutted in case of significant and sudden change in engine speed and therefore the importance of centrifugal forces. With respect to said stops, it is important that they be stable and distributed in places favorable to balancing the efforts, particularly in the potentially critical situation above, in order to prevent any jamming situation of the platforms. It is therefore recommended that the rotary assembly in question comprise: an upstream ferrule integral in rotation with the disk, a low-pressure compressor drum, with: inter-blade platforms retained radially, rotary assembly rotating, by abutting against portions of the upstream shell and the drum which will belong to said radially outer stops.

3037367 5 With the principle of the above solution, the protective lining serves as a "shield" to the disk so that it does not break down. However, the number of these parts being important, there is a risk of non-quality and especially of loss of time in case of assembly in the wrong direction along the tooth concerned. A proposed solution is that each protective lining: - is elongated parallel to the axis about which the disk is mounted rotating, - and has: - at a first end following this elongation, a fold of material which abuts against an outgrowth of the corresponding tooth, if said protective lining is mounted in the correct direction along the corresponding tooth of the disk, and, at a second end opposite to the first along said elongation, an extension of keying material which, if the protective lining is mounted against the direction along said tooth, encroaches on a space of the tooth reserved for maintaining a lock useful for a frontal retention of one of said blades and thus preventing this maintenance.

It will be appreciated that if a protective lining is mounted in the wrong direction, the misplaced material fold may be inoperative with respect to a possible scratching of the disk. In addition, the fold of material found at the opposite of its normal position, it could damage the platform that will cap it.

In addition, during the assembly sequence, the protective liners, then the blades, then the bolts and at the end of the axial blades of the blades will typically be mounted. To avoid that, if a protective lining is incorrectly fitted, several elements will have to be dismantled, it is recommended that the flanks of the teeth have notches which will keep the latches engaged therein only if the protective lining is mounted 3037367 6 in common sense along said teeth. Otherwise, these locks can not be engaged in the nicks. The protruding material extensions will prevent it. A favorable application of the above is also to be found in the case where the disk and the blades will be those of a turbomachine fan. Indeed, the problems of risk of aerodynamic (s) including rising (s) are all the more critical that the fluid flow is important and it is located at the inlet of the oxidizer circuit in the 10 engine. Other advantages and features of the invention will become apparent on reading the following description given by way of nonlimiting example and with reference to the appended drawings, in which: FIG. 1 is a partial diagrammatic view in axial section (axis 15 longitudinal A of the engine) of an exemplary turbomachine input stage according to the invention; FIG. 2 is a perspective view of a fan disk; - Figure 3 is an enlargement of Figure 2, with a blade provided with an adjacent platform; Figure 4 is a same view, still enlarged, from the front; - Figure 5 is a same view still enlarged, in section along V-V; - Figures 6-7 are two local sections in the plane 100 of Figure 1 through which the axis A; FIGS. 8 and 9 show schematically the foolproofing effect provided by the linings, when they have been properly mounted (FIG. 8), and FIG. 10 is a substantially radial grease packing solution. Referring firstly to Figure 1 which shows a turbine engine inlet stage 10. The stage is arranged around a central axis A of revolution, around which are arranged the various elements constituting the stage 10, in this case the stage of the fan of the turbojet 3037367 7 schematically. The upstream is located in the figure on the left (AM), meaning where the fluid flow coming through the turbomachine in operation comes from. The downstream (AV) is on the right. A rotary drive shaft 12 is arranged radially inside the stage. This shaft is conventionally driven by a turbine of the turbomachine, further downstream. The shaft 12 transmits the rotational movement to the rotating parts of the input stage 10. As a result, a disc 14 is arranged around the shaft 12, and is rotatably connected thereto through the intermediate shaft. example of grooves 12A, 14A. The disk 14 comprises at its outer periphery a circumferential alternation of teeth 18 and grooves 20 which extend elongate substantially parallel to the axis A, as can also be seen in FIG. 2. The radially inner walls of the grooves are called grooves, 22. Blades 24, whose feet 26, plump, are engaged axially 15 in the grooves 20 and retained radially by the teeth 18, extend radially around the disc 14, as shown schematically in FIG. forms 28 furthermore extend circumferentially between each pair of adjacent blades 24. The platforms 28 are elongate, from upstream to downstream of the vanes 24, so as to form the internal boundary of a gas flow line 30 of the turbomachine (see FIG. 1). The platforms 28 extend along the vein 30 the hood or upstream conical nose 36 of the fan to the drum or rotor 37 of the low pressure compressor. The cone 36 is arranged upstream of the shaft 12 of the disc 14 and the blade roots 26. This cone 36 forms the inner 25 and upstream limit of the vein 30. In the presence of a blower, the vein 30 is a external vein. Thus, in this case, a nacelle 32 surrounds the radially outer ends of the blades 24. More particularly, an annular wall 34 of the nacelle 32 forms the outer limit of the vein 30, and extends with a slight clearance around the outer ends 24 to prevent gases 3037367 8 from circulating from upstream to downstream radially between the vanes 24 and the nacelle 32. In FIG. 3, the teeth 18 and grooves 20 are roughly schematized, as is blade 24 mounted in its receiving groove 5 20, with a platform 28, on one side. The trims 50 presented below are not shown. FIG. 4 shows better the position of such a platform 28. And FIGS. 8, 9 show that for the axial retention of the vanes 24 in the grooves 20 of the disc 14, means 37 upstream axial retaining 10 of these vanes are furthermore advantageously provided. As will be described in more detail below, the means 37 may comprise an annular flange (not shown) often referred to as the hood rear ferrule head and latches 40. FIGS. 28 inter-blades are mounted radially movable between radially outer 42 and inner 44 stops, respectively. For its radial retention, each platform 28 is, in the illustrated embodiment, mounted between: - internally, the outer surface 180 of a tooth 18, which defines one of the abutments 44, - and externally: - a Upstream ferrule 48 integral in rotation with the disk, which holds the platform towards its upstream end 280a, and the drum 37 of low pressure compressor, which holds the platform towards its downstream end 280b. The two elements 48, 37 define the stops 42. Such a radially movable mounting of the platforms 28 will cause them, when the vanes stop rotating about the axis A, to fall back against the above-mentioned external surfaces 180 of the peripheral teeth, as shown schematically in Figure 6, in the absence of return means such as the pads 50 presented below.

In addition, when the turbomachine is operating and the vanes thus rotate around the axis A, the lateral surfaces (or sides) respectively 260 and 181 of the blade roots 26 and the lateral surfaces (or flanks) of the teeth 18. the disc then strongly wear one against the other (Figure 5), since the blades are then subjected to very large centrifugal forces and then bear against said upstream stops 48 and downstream 37. On this last point FIG. 7 makes it possible to understand and shows that each platform 28 will then be able to be radially plated: by a rim 281a of its upstream end, against an outer edge 48a of the upstream collar 48, and by a flange 281b of its downstream end, against an outer edge 37b of the drum 37 of low pressure compressor. The upstream ferrule 48 is a piece interposed axially between the air intake cone 36 and the disk 18. Optionally, the external supports of the upstream ends 280a of the platforms 28 could operate against a rim of the cone 36. Of course, the air inlet cone 36, the upstream collar 48, the disc 18 and the low pressure compressor drum 37 are fixed parts 20 secured together in rotation about the axis A. If nothing is In fact, these authorized radial movements of the platforms and the centrifugal forces, rotating rotor, will quickly lead to scratching and use the disk, via strong supports under constraints, and to create the significant risk already mentioned aerodynamic steps, 25 including rising. Also protective and support pads 50, also referred to as foils, are arranged around the teeth 18 of the disc, as shown in FIGS. 7-9 for one of the teeth and one of the platforms 28. As illustrated each liner 50 has: two sidewalls 52 each disposed between a blade root 26 and a tooth flank 181 of the disk 14 which it covers, and a transverse wall 54 capping externally the wall 180 of the corresponding peripheral tooth 18 whose sides are covered by the side walls 52 above. The gaskets 50 are typically metal parts 5 made by folding. They each have a few tenths of a millimeter thick. Furthermore, given the radial height H (FIG. 7) that exists between the wall or inner face 280c of each platform 28 and the outer wall 180 of the peripheral tooth 18 opposite, a particular conformation of each lining 50 proved necessary. Thus, it is advisable for the rotary assembly (rotor) to be both turning and stopped, the transverse wall 54 of each lining 50 has a volume shape to bear against the radially inner wall 280 of a platforms 28: each platform 15 will thus be permanently pressed against the radially outer stops, as in FIG. 7. As opposed to a plane shape (in two dimensions), this volume form (in 3 dimensions) of the wall cross-section 54, preferably coupled with the elastically deformable nature of the material of each lining 50 (steel sheet), to the one-piece construction of this lining, with its preferred U-shape with convergent branches (side walls 52, see FIG. ) and lateral rounding 56 between the parts 52 and 54, a rather strong radial spring effect will allow to counter the fallout of the platforms 28 at the engine stop.

In fact, the transverse wall 54 of each lining 50 will be favorably convex radially outwards, as illustrated in particular in FIG. 4. This will promote a distribution of forces over a fairly large area, and thus a good flexural strength.

3037367 11 And realize this convex transverse wall wall 54 in an arc will even rationalize a mass production, while securing the repeatability of maintenance operations, if necessary. However, an alternative or a complement could be as illustrated in FIG. 10 that, to enable said support, the transverse wall 54 of each lining has substantially radial protrusions 58. A greater radial height h2 could be covered and the stiffness of the gaskets 50 worked even more precisely. With FIG. 5, it will be noticed in any case that in the situation of rotating disk 14 (illustrated), each lining 50 does not bear against the outer wall 180 of the underlying tooth 18; a radial deviation hl is established, particularly at the corners, in zones 56. This avoids wear. Figures 8 and 9, we also see the preferred general external shape of each protective lining 50.

Thus, this lining is elongated parallel to the axis (A) around which is rotatably mounted the disc 14. And it has, at a first end 50a according to this elongation, a fold 60 of material which abuts against a protrusion 62 downstream of the corresponding tooth 18, if said seal 50 is mounted in the correct direction along this tooth, as shown in FIG. 8. The fold 60 is raised radially outwards, axially at the bottom of the recess 70 that the lining 50 considered present, parallel to the axis (A), at this first end 50a. Two lateral portions 68a, 68b extending in the continuity of the wall 180 laterally limit the recess 70.

In addition, at a second end 50b opposite the first end 50a, according to said elongation, the liner 50 has an extension 64 of keying material which, if the liner is counter-fitted (see FIG. said tooth, will induce an encroachment of a part of the lining 50 considered on a space 66 of the tooth.

The space 66 is reserved for holding, typically by wedging, one of the latches 40 that are useful for the frontal, axial retention of the blades 24. Impinging on the space 66 prevents this retention. Each space 66 may correspond to a notch made in a flank of the disc.

In this regard, it has already been noted further in the description that, if a liner 50 is mounted in the wrong direction, the fold 60 of misplaced material may be inoperative with respect to a possible scratch of the liner. disc 14. In addition the material fold being found at the opposite of its normal position, it could damage the platform 28 which will cap it.

In addition, during the assembly sequence, the packings 50, then the vanes 24, then the locks 40 and at the end of the axial shims (not shown) of the vanes are typically mounted. To avoid the above drawbacks and if a protective seal is incorrectly mounted, several elements are then disassembled, it is recommended that each of the two sides 181 of each tooth 18 thus has notches 66 that will maintain the locks 40 The connectors engaged therein only if the linings 50 are mounted in the correct direction along said teeth, as in FIG. 8. Otherwise, as in FIG. 9, the bolts 40 can not be engaged in the notches. The extensions 64 of keying material will prevent them. In fact, on each lining and tooth, these extensions 64 would then abut axially against the base of the projection 62 to consider the tooth 18. And each side portion 68a, 68b of the recess 70 of the lining 50, too advanced upstream, then cap one of the notches 66. In the above preferred example, the disk 14 and the blades 24 were presented as those of a turbomachine fan. Hypothetically, another part of the rotor could be made as indicated here, for example at the location of a compressor.

Claims (10)

REVENDICATIONS1. Rotary turbomachine assembly, comprising: - a rotor disc (14) circumferentially having an alternation of peripheral teeth and grooves (20), the grooves having flanks, - a plurality of blades (24) having feet mounted in the grooves, grooves, with inter-blade platforms (28) mounted radially movable between radially outer (42) and inner (44) abutments, respectively, - protective liners (50) each having: - two side walls (52); ) each disposed between a blade root (26) and a tooth flank (181) (18) of the disk (14) which it covers, and a transverse wall (54) externally capping the peripheral tooth whose flanks are covered by said side walls, characterized in that, rotating assembly both rotating and stopped, the transverse wall (54) of each protective lining (50) has a volume form to bear against a wall (280c) from one of s platforms (28), in order to press each platform against the radially outer abutments (42). 2. Rotary assembly according to claim 1 wherein for said support, the transverse wall (54) of each protective lining (50) is convex radially outwardly. 3. Rotary assembly according to claim 2, wherein the convex transverse wall (54) defines a circular arc. 4. Rotary assembly according to claim 1 or 2 wherein, for said support, the transverse wall (54) of each protective lining (50) has protrusions (58) substantially radial. 3037367 14 5. Rotary assembly according to one of the preceding claims, wherein each protective lining (50) is a one-piece piece elastically deformable, folded. 6. Rotary assembly according to one of the preceding claims, which 5 comprises: - an upstream ferrule (48) integral in rotation with the disc, - a drum (37) of low pressure compressor, and where: - the platforms (28 ) inter-blades are held radially, rotatably rotating assembly, abutting against portions of the upstream shell and the drum belonging to said radially outer stops (42). Rotary assembly according to one of the preceding claims, wherein the peripheral teeth (18) have surfaces which form an internal stop for the inter-blade platforms (28), said surfaces being protected by the protective liners (50). ) who cover them. 8. Rotary assembly according to one of the preceding claims, wherein each protective lining (50): - is elongated parallel to the axis (A) around which is rotatably mounted the disc (14), 20 - and presents: - at a first end following this elongation, a fold of material (60) which abuts against an outgrowth (62) of the corresponding tooth (18) of the disc (14), if said protective lining (50) is mounted in the correct direction along said tooth, and at a second end opposite to the first along said elongation, an extension of keying material which, if the protective liner (50) is counter-fitted along said tooth (18), encroaching on a space of the tooth reserved for holding a latch (40) useful for a frontal retention of one of said blades, and thus preventing this retention. 3037367 15 Rotary assembly according to claim 8, wherein the flanks of the teeth have notches (66) which hold the latches (40) engaged thereto if the protective linings (50) are mounted in the correct direction along said teeth ( 18). 5 10. Rotary assembly according to one of the preceding claims, wherein the disk and the blades (24) are those of a turbomachine fan.