FR3039201A1 - THERMAL PROTECTION TURBOMACHINE PART HAVING PINS - Google Patents

Abstract

The invention relates to a turbomachine part comprising an annular housing (100), a distributor (800), pins (200) fixed relative to the housing, a sheet (300) of thermal protection interposed radially between the housing and the distributor. Also provided are pins (12) fixed to the thermal protection sheet (300) and extending locally around it, to radially wedge said sheet between the housing (100) and at least some pins (200) and or sectors of the distributor.

Description

PART OF TURBOMACHINE WITH THERMAL PROTECTION COVER

WITH EPINGLES

The present invention relates to the field of turbomachines and aims a turbomachine part comprising a distributor, such in particular an annular axial turbine distributor.

In the present text, is axial which extends along or parallel to the longitudinal axis (X) of rotation of the relevant part of the turbomachine, which axis will be a priori the general axis of rotation of the turbomachine. Will be radial which extends radially to this axis. Furthermore, upstream and downstream references are to be considered in connection with the flow of gases in the (part of) turbomachine considered: these gases enter upstream and out downstream, circulating globally parallel to the axis longitudinal axis of rotation.

A gas turbine engine as used in aeronautics comprises an upstream inlet through which air is sucked and compressed while being guided through the compressor. The compressed air is introduced into a combustion chamber where fuel is also admitted with which the air is mixed and where the combustion takes place. The hot combustion gases are expanded in the turbine, of which generally (at least) a high pressure stage immediately downstream of the combustion chamber receives the gases at the highest temperature. Then the gases are generally relaxed again by being guided through other so-called low pressure turbine stages.

A turbine stage includes a stationary distributor wheel upstream of a turbine impeller. The gas flow is generally axial.

A distributor wheel comprises a plurality of blades arranged radially with respect to the axis of the machine connecting a radially inner annular element and a radially outer annular element. The assembly forms an annular vein opposite the moving blades of a turbine wheel. The movable wheel itself consists of vanes extending radially from the rim of a disk or a drum movable about the axis of rotation. The blades are traversed axially by the engine gases. The low pressure section of an engine thus generally comprises several turbine stages.

Typically, the distributor wheels are sectored into a plurality of sectors or segments distributed around the axis of the machine, each sector comprising a plurality of blades extending between two ring sectors. Each sector is mounted inside a turbine casing by the radially outer ring sector. The assembly is arranged to allow a relative expansion of the distributor relative to the housing, according to the speed variations of the turbomachine. Due to the axial symmetry of the distributor wheels and the tangential forces resulting from the gas flow passing through them, it is necessary to provide locking means for rotating sectors.

Patent FR 2,743,603 describes a method of mounting such distributor sectors. The distributor areas comprise a peripheral outer rib, resting on the inner wall of the housing. Clamps, formed by the downstream turbine ring at this level, hold the sectors against radial movements. A projection on the upstream face of the rib of each sector comprises a notch in which is housed a pin. This pin has an anti-rotation function which aims to prevent any rotational movement of the distributor sector around the axis of the latter.

Moreover, in order to protect the wall of the housing against the thermal radiation produced by the distributor, a sheet is interposed between the distributor and the inner wall of the housing. Downstream, this protection plate comprises a series of indentations, each with a tongue in the bottom of the indentation which rests against the anti-rotation pin corresponding sector.

If this arrangement is satisfactory in terms of maintaining the distributor inside the housing and the thermal protection thereof, it was however found that the sheet was likely to emerge from its contact with the pawn.

In WO 2011/15196, a solution is proposed; but it remains expensive and sometimes difficult to put in place.

It emerges from the foregoing that is known to date a turbomachine part having a longitudinal axis of rotation and comprising: - an annular housing, - a distributor arranged radially inside the housing and comprising a plurality of sectors arranged circumferentially around the longitudinal axis, pins fixed relative to the housing, at least one thermal protection plate interposed radially between the housing and the distributor.

Among the persistent problems, one can also note, on such a montage: - the sometimes imperfect character of the maintenance of the centering of (the) sheet (s) of thermal protection vis-à-vis the distributor to ensure an appropriate contact between the axial clamping tongues (when they exist) and anti-rotation pins, and the fact that the forming of the sheet as realized does not fully ensure on the one hand the assembly of the distributor, and secondly a sufficiently low clearance with this distributor to fully achieve the expected thermal protection function.

In addition, and in the more general context of the prior art, it can further be noted the desire to further limit the risk that the anti-rotation mount escapes the pawns of the housing.

In order to propose a solution that is relevant to all or some of these disadvantages, it is proposed that the concerned part of the turbomachine comprises pins attached to the thermal protection plate and extending locally around it, to wedge it radially between the crankcase and at least some counters and / or sectors of the dispenser.

By being fixed (s) to the thermal protection plate the (the) pin (s) will form with it a whole, to pose as a single piece.

It will also limit the risk that in particular the downstream part of the sheet escapes from its restraint and thus, not held against the pin where the tongue is, it comes rub against the inner face of the housing wall, and scratch it.

For optimized radial setting and ease of mounting pins, it is advisable that in practice, around the thermal protection plate, each pin comes radially in abutment against the pin and the dispenser sector considered.

In addition to better positioning and radial retention, optimization of axial positioning and retention must be achieved. For this purpose, it is proposed that: - parallel to the longitudinal axis (X) are defined upstream and downstream, with reference to the gas flow direction in said turbomachine part, and, that around the sheet metal of thermal protection, each pin: - comes axially in abutment, upstream, against an inner face of a rim of said sheet, - and, downstream, extends closer to a substantially radial portion the distributor sector considered a downstream end of the sheet (300) of thermal protection. Furthermore, to promote both the assembly and the effectiveness of the pins that the setting of the thermal protection plate, once in place, it is recommended that, in front of the pins, said sheet has notches in which pass the pins.

To further facilitate the establishment of the pin on the thermal protection plate, it is also advisable that each pin is defined by a folded sheet not completely closed on itself.

We can then play on a certain elasticity due to this form. Again for a final holding efficiency of the thermal protection plate and pins, or even ease of assembly, it is also proposed that each pin has radially an inner face and an opposite outer face and, axially, two opposite ends each rounded, at least one of which will extend radially on the side of the internal face of the pin considered.

For fixing between the pin and the thermal protection plate, several ways of doing things have been retained, preferably. First, it is proposed that each pin is locked under elastic stress in the manner of a clip by engagement with the thermal protection plate.

As an alternative or complement, it is proposed that each pin has opposite ends, one of which will be engaged (and maintained) under elastic stress in a slot of the thermal protection plate.

This type of solution (s) allows easy mounting of the pin, very fast therefore inexpensive, without damaging the thermal protection plate. Once mounted, the pin is captive and can not be removed without special handling, which guarantees the mounting of the sheet with its pins and allows to constitute a single piece to install in the space between the distributor and the crankcase.

Alternatively, it is also proposed that at least some of the pins are fixed by welds to the thermal protection plate.

Alternatively, it is further proposed that at least some of the pins are secured by rivets to the thermal shield.

Welding or riveting operations are well-controlled and reliable procedures. The invention also relates to a gas turbine engine comprising a turbine stage corresponding to this turbomachine part.

If necessary, the invention will be better understood and other characteristics, details and advantages thereof will become apparent upon reading the following description, given by way of non-limiting example and with reference to the accompanying drawings, in which: which: - Figure 1 is an axial sectional diagram of a known gas turbine engine on which the pin solution (s) of the invention can be applied; - Figure 2 is a partial axial sectional view of a low pressure turbine section according to Figure 1, at its outer circumference; FIG. 3 is a view in the direction of the axis of the engine of the dispenser of FIG. 2 with a part torn off; - Figure 4 is a sectional view as Figure 2, more localized, where the protective plate, one of the anti-rotation pins and a pin according to the invention are illustrated, mounted in the relevant part of the turbomachine, - Figures 5 and 6 show a possible realization of the area between one of the pins and the protective plate (seen from below Figure 6), - and Figures 7,8,9 show three possible assemblies between a pin and the protection plate.

Referring first to Figure 1, there is schematically a gas turbine engine 1 of the turbofan type. This turbomachine comprises, upstream (AM) downstream (AV), along the longitudinal axis X, which is an axis of rotation: a fan 2, a low pressure compressor 3, a high pressure compressor 4 , a combustion chamber 5, a high pressure turbine 6 and a low pressure turbine 7.

The low-pressure turbine 7 may comprise several mobile stages on the same rotor and thus drive, via a central shaft, the assembly formed by the fan 2 and the low-pressure compressor 3.

The high-pressure turbine 6, with only one stage in the example, independently drives the high-pressure compressor 4.

As illustrated in FIG. 2, the low pressure turbine section 7 comprises a distributor 8 or stator.

This distributor 8 is upstream of a wheel provided with blades 9 and disposed inside the casing 10 of the turbine. The moving wheel rotates about the X axis (Figure 1), inside a turbine ring 9 '.

The distributor 8 is formed of vanes arranged in a wheel divided into a plurality of sectors 80a, 80b ... (Figure 3) distributed around the axis of the machine, circumferentially. Each sector comprises several adjacent fixed vanes integral with a ring sector element 81 (FIG. 2).

Like the other sectors, the sector 80a distributor is maintained upstream by a rib shaped rail 101 extending axially from a substantially radial rib 103 of the inner wall of the housing 10. An upstream hook 82 secured to the ring sector element 81 bears against a radially outer face of the rail 101. Downstream, the element 81 comprises a peripheral radial rib 83, perpendicular to the axis (X) of the distributor, which is supported by a radially outer face 83a and a downstream face 83b on corresponding faces of an annular rail 102 which extends axially from the inner wall of the housing 10 with a downstream edge turned towards the axis. One of a series of anti-rotation pins 20 is housed in a housing 11, here radial, housing 10. The pin 20 is projecting inside the housing and engages in a notch 83c machined in the rib 83 of sector 80a (FIG. 3).

The pin 20 is fitted tightly in the housing 11 of the housing but also in the notch 83c. It comprises two flanks which are slid between the flanks of the notch machined parallel to the axis of the distributor. The screen is open upstream and is located in the center of the area. In this way each sector is kept fixed in rotation relative to the housing while being able to expand circumferentially, on either side of the pin, and to move axially to a certain extent.

A thermal protection plate 30 is disposed between the ring sector 81 of each sector, as here that 80a, and the inner wall of the housing.

The sheet has a generally ring-shaped shape which upstream rests against an abutment surface formed in the housing which may be at the level of the upstream rail 101. Downstream, the protective plate 30 is cut off in a series of indentations along the contour of the projection 83 'of the corresponding rib (Figure 3). A tongue 30a in the bottom of the notch bears against the anti-rotation pin 20 considered. The sheet being slightly deformable, a spring effect can be provided to ensure the maintenance of the sheet during operation of the turbomachine.

In FIGS. 4 et seq., It is no longer the prior art, but a possible assembly according to the invention, it being specified that the identical parts, in their function and / or their structure, to those mentioned above have received the same reference increased by one hundred.

As shown in FIG. 4, a pin 12 among here a series of identical pins is fixed to the thermal protection plate 300 and extends locally around it, to wedge radially this sheet of thermal protection 300 between the housing 100 and some at least sectors of the distributor 800 and / or pins 200.

Thus, the sheet 300 will be able to be radially maintained more precisely in the annular space 13 which extends radially between the housing 100 and the sectors of the distributor 800. The pins 12 will refocus the sheet 300 on the distributor, limiting the games between it and this distributor.

In this solution, there is an annular housing 100 having a housing 110 for the pin 200 illustrated. And a plurality of sectors (such as 800a in FIG. 5) of distributor 800, each in the form of a ring sector, are distributed circumferentially around the axis X.

To rotate the sectors of the distributor 800 in rotation, the pins 200 can be mounted as in FIG.

The thermal protection sheet 300 is always interposed radially between an inner wall of the casing 100 and an outer wall of the sector, here 800a, of the distributor.

As preferred to best wedge the sheet 300, each pin 12 will preferably, around this thermal protection plate and the mounting clearance, in radial abutment against the pin and the distributor sector considered, as shown in Figures 4 and 6 .

It will be noted that at the radially inner end, the pin 12 will favorably, as shown in FIG. 4, bearing against the radially outer face 820a of the upstream hook 820 secured to the ring sector element 810 of the sector concerned of the dispenser 800 And as in the prior art above, this upstream hook 820 may be in contact with the rail-shaped rib 201 which extends axially from the inner wall of the housing 100.

The sectional shape of the thermal protection sheet 300, as also shown in FIG. 4, is favorable for the mounting and the effectiveness of the pins 12. In fact, this thermal protection sheet 300 has at its upstream end (AM) a spout. 14 defining a flange directed towards the X axis. At the downstream end (AV) 300c, it is better to see that the sheet 300 has a notch 16 where the pin 12 considered (Figure 6 in particular).

By the shape of the spout 14, the thermal protection sheet 300 comes axially in abutment against the substantially radial rib 203 of the inner wall of the housing 100.

Favorably, each notch 16 of the thermal protection plate 300 will be positioned facing the pin considered, as shown in FIGS. 5, 6, where the pin 200 engages in the notch 16, in the example via a substantially axial protrusion 18 of the pin . In the preferred example, each pin has a radial rod 22 engaged in the notch 16 and extended towards the space 13 by the protrusion 18.

As for the axial positioning of the pins 12, it is preferred: - that, parallel to the longitudinal axis (X) are therefore defined upstream (AM) and downstream (AV), with reference to the direction of gas flow in the turbomachine (see arrows Figure 1), and that around the sheet 300 of thermal protection, each pin 12: - comes axially in abutment, upstream, against the inner face 140 of a flange 14 of said sheet 300 and, downstream, extends closer to a substantially radial portion of the sector considered of the distributor 800 than the downstream end 300c of the sheet 300. Said substantially radial portion of the sector considered of the distributor 800 may in particular being the peripheral rib 830, substantially radial, shown in FIG. 4, which stands on the ring-sector element 810. The reduced axial clearance J which will thus be maintained with this substantially radial portion will make it possible to limit as much as possible debate axial pin of the pin in case of loss of clamping of the pin on the thermal sheet 300.

For an ease of mass production and mounting promoting an assembly between the pins and the sheet 300 of thermal protection, each pin may be defined by a thin metal sheet 24 folded not completely closed on itself, as seen in section in particular FIGS. 7 to 9. Sheet 24 may be of the same material as sheet 300, and therefore inconel ™, it being specified however that the term "sheet metal" for element 300 should not be considered as limiting the constitution to metal. .

For elasticity favorable to its maintenance and its mounting on the sheet 300, it will be preferred that each pin 12 has axially two opposite ends each with a rounded fold, respectively 26a (upstream) and 26b (downstream).

And, the thermal protection sheet 300 having radially opposite outer face 300a and inner face 300b (see in particular FIG. 7), at least one of the axially opposite ends 28a, 28b of the pin considered will extend radially, preferably the side of the inner face 300b, as shown in Figures 6 to 9. This will be favorable to the establishment of the assembly. In this regard, it will be noted that in the three solutions of FIGS. 7 to 9, which show three ways of making the pins 12 and the heat protection sheet 300 integral, each pin does not extend, from the rounding of one of the ends of the pin (here downstream 26a), only on the side of the radially inner face 300b of the sheet 300.

Figure 7, the pin is locked under elastic stress in the manner of a clip by engagement with said sheet 300 of thermal protection.

In the preferred example illustrated, the opposite ends 28a, 28b of the pin are bent and the end 28a is engaged under elastic stress in a through slot 32a of the protective plate. The opposite end 28b of the pin is, under elastic stress, bearing against the radially outer face 300a.

Such an assembly must allow easy assembly of the pin, very fast and inexpensive, without damaging the sheet 300. Once mounted, the pin 12 is imprisoned under stress and can not be disassembled without special handling, which guarantees the mounting of the sheet 300 with its pins, and allows to constitute a single piece, before positioning this assembly in the turbomachine.

The mounting of the pin concerned will preferably be carried out from the radially inner face 300b of the thermal protection sheet 300. The opposite ends 28a, 28b curved in radially outwardly directed beaks will facilitate engagement in the slots 32a, 32b1, 32b2.

Figure 8, the solution provides that the pins 12 are fixed to the sheet 300 by rivets 34. Each rivet will pass through flat portions of the pin. In the preferred example illustrated, a rivet 34 passes through: - the flat end portion 38 of the pin adjacent the end 28b which extends radially outside the sheet 300, - and an equally flat intermediate portion 40 which substantially conforms to the shape of the sheet 300 at this location. From the rounded fold 26b following the portion 38, the end 28a, the pin extends radially inside the sheet 300, to the opposite end 28a which bears against the face 300b.

Figure 9, the solution provides that the pins 12 are fixed to the sheet 300 of thermal protection by one or more welds 36. The pin is the same as riveted. Three welds can be provided: in zones 38,40 and on the extreme end of the pin adjacent the end 28a.

The clipped solution should be a priori preferred to others.

Claims (10)

1. Turbomachine part having a longitudinal axis (X) of rotation and comprising: - an annular casing (100), - a distributor (800) arranged radially inside the casing (10) and comprising a plurality of sectors (20). ) arranged circumferentially about the longitudinal axis (X), - pins (200) fixed relative to the housing (100), - a sheet (300) of thermal protection interposed radially between the housing and the distributor (800), characterized in that it further comprises pins attached to the thermal protection sheet (300) and extending locally around it, to radially wedge the thermal protection sheet (300) between: - the casing (100), and at least some sectors of the dispenser (800) and / or pawns (200). 2. Turbomachine part according to claim 1, wherein around the sheet (300) of thermal protection, each pin (12) is radially abutting against the pin (200) and the distributor sector (800) considered. 3. Turbomachine part according to claim 1 or 2, wherein: parallel to the longitudinal axis (X) are defined upstream and downstream, with reference to the direction of gas flow in said turbomachine portion, and, around the sheet (300) of thermal protection, each pin (12): - comes axially in abutment, upstream, against an inner face (140) of a flange (14) of the sheet (300) of thermal protection - and, downstream, extends closer to a substantially radial portion of the distributor sector (800) considered a downstream end of the sheet (300) of thermal protection. 4. Turbomachine part according to one of the preceding claims, wherein each pin (12) is defined by a folded sheet not completely closed on itself. 5. Turbomachine part according to claim 4, wherein each pin (12) has radially an opposite inner face and an opposite outer face and, axially, two opposite ends (28a, 28b) each rounded, at least one of which extends. radially on the side of the inner face of the pin (12) considered. 6. Turbomachine part according to one of the preceding claims, wherein facing the pins (200) the plate (300) of thermal protection has notches (16) in which pass the pins (12). 7. Turbomachine part according to one of the preceding claims, wherein each pin (12) is locked under elastic stress in the manner of a clip by engagement with the sheet (300) of thermal protection. 8. Turbomachine part according to claim 4 or 7, wherein each pin (12) has opposite ends (28a, 28b), one of which is engaged under elastic stress in a slot (32a) of the sheet (300) of thermal protection. 9. Turbomachine part according to one of claims 1 to 6, wherein the pins (12) are fixed by welds (36) to the sheet (300) of thermal protection. 10. Turbomachine part according to one of claims 1 to 6, wherein the pins (12) are fixed by rivets (34) to the sheet (300) of thermal protection.