EP4022176B1 - Turbine arrangement incorporating an oil recovery circumferential trough - Google Patents

Description

TECHNICAL AREA

The invention relates to turbine equipment comprising a journal provided with a flange carrying a bladed disc in a turbomachine such as a turbojet.

STATE OF PRIOR ART

WO2015007980A1 discloses a device for protecting against oil leaks towards the rotors of a turbomachine turbine.

FR2992679A1 discloses a turbomachine journal comprising a crown for recovering a flow of lubricating oil.

A turbofan engine has an inlet sleeve receiving air which is sucked in by a low-pressure compressor, to then be divided into a central primary flow and a secondary flow surrounding the primary flow.

After passing the low pressure compressor, the secondary flow is propelled backward to directly generate thrust by being blown around the primary flow.

After passing the low pressure compressor, the primary flow passes through a high pressure compressor to reach a combustion chamber. This primary flow is then expanded in a high pressure turbine linked in rotation with the high pressure compressor, then in a low pressure turbine linked in rotation with the low pressure compressor, before then being expelled backwards.

In the case of a twin-spool turbojet, the high-pressure compressor and the high-pressure turbine are part of a high-pressure body which surrounds a low-pressure shaft, rotating at a speed different from the latter, this low-pressure shaft carrying the low pressure compressor and low pressure turbine.

The shaft and the high pressure body are carried by bearings housed in enclosures isolating them from the rest of the engine, in which oil circulates. Generally speaking, such a lubrication enclosure contains at least one bearing and is delimited by walls rotating relative to each other with a seal between these walls, which limits the leakage section of the enclosure. The oil is moved away from the seal by means of a stream of air constantly entering through this seal, from the outside to the inside of the enclosure.

In the event of a leak at such a joint, the oil present in the enclosure is centrifuged, so that it is likely to come closer to regions surrounding the primary vein subject to high temperatures, thereby potentially igniting this oil.

For this reason, the shapes of the engine components are designed to delimit preferential leak paths ensuring that in the event of a leak, the oil is directed to areas of the engine where it does not pose a risk to its operation.

In practice, the blades of the low pressure turbine are carried by a turbine disk which is itself fixed to a flange of a journal which passes through it, this journal being carried by one or two bearings and rigidly secured to the shaft low pressure.

In this context, a preferential leak path starts from a joint of a bearing enclosure located upstream of the low pressure disc. This leak path runs along the internal faces of different rotating components having internal diameters which increase downstream, which makes it possible to direct the oil towards the rear of the engine by centrifugation effect to collect it there without it does not reach the primary vein. Additionally, a flow of air blown into this path helps to carry this oil backwards.

During this path the oil passes longitudinally through the pin, at the level of the flange of this pin, through evacuation holes formed in the body of the pin, these evacuation holes being located radially inside an interior edge of the disc and an inner edge of the flange.

Although the turbine disk has a flat face clamped against a flat face of the flange by a series of circumferential bolts, it cannot be excluded that oil may pass through by centrifugation and/or capillary action.

Thus, oil present at the junction of the disc and the flange is likely to infiltrate radially between their bearing faces, thus arriving in a zone with a high risk of inflammation, potentially weakening the disc. , the blades and their connections.

The aim of the invention is to provide a solution to limit such a risk.

STATEMENT OF THE INVENTION

For this purpose, the subject of the invention is a turbine arrangement comprising a low pressure journal having a flange, and a disc fixed to this flange by a bolted connection, characterized in that it comprises a fixed circumferential channel extending around of the bolted connection to collect oil capable of traveling radially through this bolted connection.

The invention ensures that oil leaking through the bolted connection is collected in the channel, so that it is not likely to spread to the primary vein where it could ignite.

The invention also relates to an arrangement thus defined, in which the disc includes a dropper located opposite the channel, and/or in which the flange includes a dropper located opposite the channel. screw the channel.

The invention also relates to an arrangement thus defined, comprising a lubricated bearing located in an enclosure surrounding this pin and by which this low pressure pin carries a high pressure pin, oil from the enclosure being capable of leaking through the bolted connection.

The invention also relates to an arrangement thus defined, in which the channel comprises an annular bottom and two sides in the form of flared crowns which are carried by this bottom.

The invention also relates to an arrangement thus defined, comprising an evacuation conduit connected to the channel and passing through a fixed blade of the turbine, this conduit extending from a lower portion of the channel to a lower portion of the turbine.

The invention also relates to an arrangement thus defined, in which the lower portion of the channel comprises a drainage hole extended by an external cannula engaged in an upper end of the conduit.

The invention also relates to an arrangement thus defined, in which the channel comprises a counterbore surrounding the external cannula, and in which the conduit is connected to the counterbore by a ball joint connection.

The invention also relates to an arrangement thus defined, in which the channel comprises a longitudinal groove positioned downstream of the evacuation conduit relative to the direction of circulation of the oil in the channel.

The invention also relates to a turbomachine comprising a turbine disk thus defined.

The invention also relates to a turbojet comprising a turbomachine thus defined.

BRIEF DESCRIPTION OF THE DRAWINGS

• Figure 1 is a half-sectional view of a rear part of an engine in accordance with the arrangement according to the invention;
• Figure 2 is a local sectional view of a region comprising a bearing interposed between two journals in the arrangement according to the invention;
• Figure 3 is a local sectional view showing the arrangement of the channel with its discharge conduit in accordance with the invention;
• Figure 4 is a sectional view showing the connection of the conduit to the channel in accordance with the invention;
• Figure 5 is a sectional view showing the attachment of the exhaust duct to an external fixed blade base.

DETAILED DESCRIPTION OF PARTICULAR EMBODIMENTS

On the figure 1 , a rear part 1 of a motor according to the invention comprises an interior envelope 2 surrounded by an intermediate envelope 3 which jointly delimit a primary vein.

This rear part comprises a high pressure turbine 4 comprising a disk 5 carrying rotating blades, followed by a double-stage low pressure turbine 6, comprising a first distributor 7 followed by a first rotating stage 8 and a second distributor 9 which is followed by a second rotating stage 10. The first and second distributor 7 and 9 are formed of fixed vanes 11 and 12 passing radially through the primary vein.

The first rotating stage 8 comprises a series of blades 13 extending radially in the primary vein and carried by a first rotating disk 14 located inside the casing 2. Similarly, the second rotating stage 10 comprises a series of blades 16 carried by a second rotating disk 17 also located in the interior envelope downstream of the first disk 14.

Downstream of this low pressure turbine is located an exhaust casing 19 comprising an internal shroud and an external shroud as well as radial arms 18 securing these shrouds to each other. The external shell delimits a portion of the intermediate envelope 3, the internal shell delimits a portion of the internal envelope, the radial arms passing radially through the primary vein.

This exhaust casing 19 supports in its central region a bearing 21 which carries a low pressure journal 22, also extending inside the inner casing, and to which the first and second low pressure turbine disks are fixed 14, 17.

The first disc 14 is rigidly secured to an upstream face of a flange 23 of the pin 22, and the second disc 17 is secured to a downstream face of this same flange 23. This fixing is ensured by a bolted connection 24 comprising bolts 25 each passing through the first disk 14 at its internal periphery, the flange 23 at its external periphery, and the second disk 17 at its internal periphery.

The disc 5 of the high pressure turbine is carried by a high pressure journal 26 having a downstream end 27 which surrounds a middle portion 28 of the low pressure journal 22. The middle portion 28 of the low pressure journal 22 carries the downstream end 27 of the journal high pressure 26 by means of a lubricated intershaft bearing 29 comprising a roller bearing which is interposed between the downstream end 27 and the middle portion 28.

The bearing of the bearing 29 is located in a lubrication enclosure 30 which is closed upstream by an upstream seal 31 and downstream by a downstream seal 32. The element seal 31 surrounds the pin 22 and is surrounded by the pin 26, while the downstream seal 32 surrounds the end 27 and is surrounded by an internal ring carried by the low pressure pin 22. In the event of damage to the downstream seal 32 , the oil leaks from this downstream joint 32 towards the upstream AM to then be centrifuged and directed towards the downstream AV of the engine, according to a preferential leak path marked by F, to finally reach a collection region 33 close to the internal shroud of the exhaust casing 19.

As visible more precisely on the figure 2 , along this path F, the oil first passes through the high pressure pin 26 at the level of evacuation holes 34 provided for this purpose, before reaching a skirt 36 of a ferrule 37 which is carried by the low pressure pin 22. The oil runs along an internal face of this skirt 36 before passing through the low pressure pin 22 via longitudinal through evacuation holes 38 which it includes for this purpose. When it travels along the skirt 36, the oil also passes through holes 39 in the ferrule 37 located between the skirt 36 and the internal ring, marked 40, of this ferrule 37.

As visible in the figures, the skirt 36 has a free end which surrounds a sealing element 35, and in a similar manner the internal ring 40 has an end which surrounds the sealing element 32 of the enclosure 30. This ferrule 37 constitutes a wear element, that is to say abradable which slides on the sealing elements 35 and 32, and must be changed during the life of the engine.

After passing the evacuation holes 38, the oil runs along a flange of revolution 41 extending inside the second disc 17 carried by the low pressure pin 22, to then reach region 33.

As visible on the figures 1 and 2 , along this path F, the oil runs along the internal faces of rotating components whose diameters increase from upstream to downstream, so that it is the centrifugation of the oil which allows it to be conducted downstream where the collection region 33 is located. This path is also favored by a ventilation flow V which is established from upstream to downstream in this path.

The assembly arrangement of the first disc 14 with the flange 23 integrates the fixing of the ferrule 37 which comprises a fixing crown 42 applied against an upstream face of the flange 23, being clamped between an internal crown 43 of the disc 14 and this flange 23. The second disc 17 comprises an internal crown 44 which is applied against a downstream face of the flange 23.

The assembly is held by the series of longitudinal bolts 25 regularly distributed circumferentially along the flange 23, each bolt passing through the internal crown 43 of the first disc 14, the fixing crown 42, the flange 23, and the internal crown 44 of the second disk 17.

Despite the tightening of these bolts 25, the oil can leak radially passing between the crown 42 and the flange 23, this leak flow being marked by F' in the figures.

According to the invention, the turbine is equipped with a circumferential channel 45 which extends around the flange 23, being opposite the bolted connection 24 of the disc 14 with this flange 23. This channel 45 collects thus the oil likely to leak radially through this connection 24, that is to say between the crown 43 of the disc 14 and the flange 23 to which this crown 43 is fixed.

This channel 45 comprises an annular bottom 46 carrying an upstream side 47 and a downstream side 48, these two sides being sheet metal elements having the shape of crowns fixed by brazing to the bottom 46 and constituting the cheeks of the channel. Thus, when seen in longitudinal section as on the Figure 3 , the flange has a U- or V-shaped section. More particularly, the upstream side 47 has the shape of a crown whose internal portion flares towards the upstream, and the downstream side 48 also has the shape of a crown but whose internal part flares downstream. The annular bottom 46 has a substantially rectangular shape in section having a significant thickness radially and longitudinally.

The channel 45 is carried by a fixed element of the engine, linked to the inner casing 2. In the example of the figures, the channel 45 is carried at the level of its upstream flank by an upstream annular support element 49 ensuring sealing with the first disk 14 and it is carried at the level of its downstream side 48 by a downstream annular support element 50 ensuring sealing with the second disk 17. These annular support elements 49 and 50 are identified on the Figure 3 .

As visible on the figures 1 and 2 , the channel 45 surrounds the flange 23 while being positioned longitudinally at the junction of the crown 42 with the flange 23. In other words, the upstream side 47 is located upstream of this junction, while the downstream side 48 is located in downstream of this, so that the channel 45 collects the oil leaking radially through this junction.

Complementarily, and as shown on the Figure 3 , the disc 14 is provided with a drip nozzle 51 located substantially upstream AM of its junction with the flange 23 and to the right of the flared internal portion of the upstream side 47. Similarly, the flange 23 comprises another nozzle drops 52 located downstream AV of its junction the disc 14 and to the right of the flared internal portion of the downstream side 48.

Each drip nozzle is a radial rim extending around the entire circumference of the disc and flange, respectively, to ensure that oil travels to the outer face of the disc or flange from the junction area , or projected into the channel 45 by centrifugation. In certain configurations, it is possible to provide either only the amnot dropper 51, or only the downstream dropper 52.

The arrangement also includes an evacuation conduit 53 extending radially relative to the axis of rotation AX of the motor. This conduit has an internal radial end connected to the bottom 46 of the channel, and an external radial end connected to a collection tank 54 located radially at a distance from the primary flow to be in a cold part of the engine, as illustrated schematically on the figure 1 .

The oil collected by the channel 45 is thus recovered in the tank 54, in particular to avoid dispersing it in the atmosphere surrounding the engine. The conduit 53 is located circumferentially at 6 o'clock, that is to say it extends vertically from a lower portion of the channel 45 to a lower portion 66 of the engine where the tank 54 is located, so to recover the oil by gravity.

As shown more precisely on the figure 4 , the lower portion of the channel 45 has a drainage hole 55 passing through its bottom 46, which is extended by a cannula 56 opening out on the side of the external face of the bottom. This cannula 56 is engaged in an internal or upper end of the conduit 53, so as to ensure that all the oil drained into the hole 55 enters the interior of the conduit 53 without risk of dripping along its external face. This cannula 56 extends in a countersink 57 formed on the external face of the bottom 46 coaxially with the hole 55, so that it does not protrude from the external face of the bottom 46.

Additionally, the internal end of the conduit 53 has a locally spherical shape to constitute a ball joint 58 of diameter complementary to that of the countersink 57, which allows this end to engage in a sealed manner in the countersink 57 despite a lack of orientation of the conduit 53.

Complementarily, and as illustrated schematically on the Figure 5 , the annular bottom 46 of the channel 45 is provided on its internal face with a longitudinal groove 59. This groove 59 makes it possible to slow down the oil located in the channel 45 which tends to rotate in the direction of the rotor due to its ejection by centrifugation. This groove is advantageously located downstream of the countersink 57 relative to the direction of circulation of the oil in the channel 45, so as to promote the evacuation of the oil through the conduit 53 by slowing it down in the vicinity of the hole.

Alternatively to the groove 59, it is possible to provide tangential recovery of the oil in the channel, for example by providing a scoop and/or an inclination of the drainage hole 55.

The conduit 53 passes through an internal base 60 of the fixed blade 12 visible on the Figure 3 to travel inside this fixed blade 12 and cross the external base 61 of this fixed blade 12 which is visible on the figure 5 , before passing through the intermediate envelope 3, comprising a casing 62 surrounding the low pressure turbine.

As illustrated on the Figure 5 , the radially external end of the conduit 53 is fixed to the casing by bolting, being surrounded by an external nut 63 placed on the external face of the casing 62, and it is connected to a collection pipe 64 itself connected to the tank 54 .

Furthermore, the conduit 53 is advantageously heat-insulated or made of double skin so that the oil circulating there does not risk catching fire or solidifying by hardening.

Alternatively or additionally, we can have a distributor 9 cooled by air coming from the pipe supplying the distributor 11 and passing through the attachments of the distributors 9 and 11 close to the envelope, as illustrated in the figure 1 by arrows marked by R.

Claims (10)

1. Turbine arrangement comprising a low-pressure trunnion (22) having a flange (23), and a disc (14) fixed to this flange (23) by a bolted connection (24), characterised in that it comprises a fixed circumferential trough (45) extending around the bolted connection (24) for collecting oil that is capable of travelling radially through this bolted connection (24).
2. Arrangement according to claim 1, wherein the disc (14) comprises a dropper (51) located opposite the trough (45), and/or wherein the flange (23) comprises a dropper (52) located opposite the trough (45).
3. Arrangement according to claim 1 or 2, comprising a lubricated bearing (29) located in an enclosure (30) surrounding this trunnion (22) and by which this low-pressure trunnion (22) supports a high-pressure trunnion (26), oil from the enclosure (30) being potentially capable of leaking through the bolted connection (24).
4. Arrangement according to any of the preceding claims, wherein the trough comprises annular base (46) and two flared ring-shaped flanks (47, 48) which are supported by this base (46).
5. Arrangement according to any of the preceding claims, comprising a discharge duct (53) connected to the trough (45) and passing through a fixed blade (12) of the turbine, this duct (53) extending from a lower portion of the trough (45) to a lower portion (66) of the turbine.
6. Arrangement according to claim 5, wherein the lower portion of the trough (45) comprises a drainage hole (55) extended by an outer cannula (56) engaged in an upper end of the duct (53).
7. Arrangement according to claim 6, wherein the trough comprises a counterbore (57) surrounding the outer cannula (56), and wherein the duct (53) is connected to the counterbore by a ball joint (58).
8. Arrangement according to claim 5, wherein the trough (45) comprises a longitudinal groove (59) positioned downstream of the discharge duct (53) relative to the direction of circulation in the trough (45) of the centrifuged oil.
9. Turbomachine comprising a turbine disc (14) having an arrangement according to claim 1.
10. Turbojet engine comprising a turbomachine according to claim 9.

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