EP2368017A1

EP2368017A1 - Positioning member for ring segment

Info

Publication number: EP2368017A1
Application number: EP09795477A
Authority: EP
Inventors: Jean-Baptiste Arilla; Denis Chanteloup; Yvan Lameignere
Original assignee: Turbomeca SA
Current assignee: Safran Helicopter Engines SAS
Priority date: 2008-11-21
Filing date: 2009-11-20
Publication date: 2011-09-28
Anticipated expiration: 2029-11-20
Also published as: US20110236203A1; ES2423794T3; EP2368017B1; FR2938873A1; US9051846B2; WO2010058137A1; CN102224323B; RU2011125322A; RU2516992C2; CA2744413C; FR2938873B1; KR101723366B1; KR20110084994A; PL2368017T3; JP5628190B2; CA2744413A1; JP2012509435A; CN102224323A

Abstract

The present invention relates to a positioning member (10) of a ring segment for a turbine wheel rotatably mounted about an axis in a housing. The invention is characterised in that the member has: an attachment portion (20) intended for being attached to the housing; a resilient portion (24, 26, 28) forming a spring; a support portion (30, 32) connected to the resilient portion and intended for engaging axially with the ring segment, such that, when said member is mounted, the ring segment is axially clamped against a portion of the housing by the positioning member.

Description

Positioning member for ring segment

The present invention relates to the field of turbomachine turbines, and more particularly those found in gas turbines.

The present invention more specifically relates to a turbomachine comprising a member for positioning a ring segment for a turbine wheel rotatably mounted about an axis in a housing. Traditionally, turbomachine turbine wheels, such as helicopter gas turbine high pressure turbines, are encircled by a ring concentric with the turbine wheel. This ring, as a constituent element of the stator of the turbomachine, forms an outer shell for the turbine stage. In other words, the flue gases exiting the combustion chamber flow between the hub of the turbine wheel and the ring so as to drive the turbine wheel in rotation.

Generally, the ring is constituted by a plurality of ring segments, also called ring sectors, arranged contiguously next to each other.

These ring segments are generally not fixed integrally to the casing of the turbomachine because they are likely to expand axially and radially due to the large heat carried by the flue gases. In fact, the ring segments are held in the housing by one or more positioning members.

Furthermore, it is usually intended to cool the ring segments by circulating a cooling fluid around the ring, this cooling fluid can for example be taken from the compressed air that is generated by the compressor of the turbomachine .

However, such an arrangement has the disadvantage of creating leakage zones and it is conceivable that the burnt gases can enter the cooling circuit or conversely, the cooling fluid can enter the gas stream arranged. upstream or downstream of the turbine wheel, which penalizes the efficiency of the turbomachine, with a greater penalty in the case of ejection downstream.

In order to prevent leakage, US Pat. No. 5,988,975 proposes a solution which consists in producing a radial seal thanks to a ring which keeps the ring segments in radial abutment against the casing.

An object of the present invention is to provide a turbomachine comprising an alternating positioning member for sealing between a gas stream and the cooling circuit. The invention achieves its goal by the fact that the positioning member has:

an attachment portion intended to be fixed to the housing;

an elastic portion forming a spring;

a bearing portion connected to the elastic portion and intended to abut axially against the ring segment, so that, when said member is mounted, the ring segment is axially pressed against a portion of the housing by the positioning member.

For the purposes of the present invention, the terms "axial" and "radial" are considered with reference to the axis and a radius of the turbine wheel, while the term "downstream" is referred to in the sense of flue gas flow in the turbine.

Thus, since each ring segment is held axially against a portion normal to the axis of rotation (downstream or upstream) of the casing, thanks to the axial force exerted by the bearing portion of the positioning member, it follows that the seal is made between the cooling fluid circuit and the gas stream.

In other words, the positioning member being fixed to the housing by the fixing portion, the axial force generated by the elastic portion is transmitted to the bearing portion and the ring segment. The latter being able, in the absence of the positioning member, to move slightly axially relative to the housing, it is conceivable that the support portion pushes the ring segment against the part of the housing, as a result of which it is pressed against said housing part. Preferably, the bearing portion pushes the ring segment against the downstream portion of the housing. According to another variant, the fixing portion also bears against the ring segment.

Preferably, the elastic portion is disposed between the attachment portion and the bearing portion. Preferably, the portion of the housing against which the ring segment is plated is normal to the axis of rotation of the turbine wheel. Advantageously, the positioning member according to the invention comprises at least a first arm carrying the fixing portion.

Preferably, this first arm is intended to extend preferably axially.

According to a first variant, the attachment portion is in the form of a tab extending orthogonally with respect to a plane in which the first arm extends.

Thus, when the positioning member is mounted, the tab extends radially. It is especially intended to be clamped between two constituent parts of the housing.

According to another variant, the fixing portion comprises a bore whose axis extends orthogonally with respect to a plane in which the first arm extends. In this variant, the attachment to the housing is carried out for example but not exclusively by means of a screw-nut system, so that the first arm of the positioning member is locked axially relative to the housing.

Advantageously, the elastic portion consists of a corrugated tongue, this tongue being for example a thin metal plate, for example a flexible sheet, having several successive folds. However, other types of elastic portion could be conceived.

Moreover, the corrugation is preferably arranged between the fixing portion and the bearing portion. According to a first embodiment, the positioning member is in the form of a tongue whose first end, constituting the fixing portion, has an orthogonal tab, whose second end, constituting the bearing portion, is curved, and whose middle portion disposed between the first and second end is corrugated so as to constitute the elastic portion. According to another embodiment, the positioning member comprises at least one first arm carrying the fixing portion, and at least one second arm comprising the elastic portion, the latter being preferably formed by a corrugation.

According to an advantageous aspect of the invention, the first and second arms are parallel and extend from a plate, the attachment portion is located at one end of the first arm opposite the plate, while the support portion is located at the end of the second arm opposite the platen.

An interest that the fastening portion (including the point of attachment of the positioning member to the housing) is close to the bearing portion, is that the effects of the deformation (thermal effect) of the housing, the segments or positioning system between the support portion and the attachment portion. This limits the efforts applied to the segments and consequently improves the holding of the ring segments.

Preferably, the positioning member further comprises a third arm similar to the second arm which extends from the plate, the arms being arranged so that the first arm extends between the second and third arms. Thus, the positioning member has the shape of an "E", where the three branches are constituted by the first, second and third arm. More specifically, these three arms extend axially when the positioning member is mounted with the ring segment.

An advantage of this positioning member is that it also makes it possible to azimuthally retain two consecutive ring segments. To do this, each of the ring segments is held in an azimuthal direction between the first arm of a first positioning member located at one end of the segment and the first arm of a second positioning member located at the end of the segment. other end of the segment.

Furthermore, the first arm furthermore preferably comprises a second elastic portion disposed between the plate and the fixing portion, whereby the elasticity of the positioning member is further improved. In another embodiment of the invention, the first arm forms a wafer for covering a gap junction defined between two contiguous ring segments, in which case one of the ends of the wafer preferably carries the tab mentioned above. to allow the fixing of the positioning member to the casing Thus, the plate improves the seal by covering the gap that may exist between the two ends of two contiguous segments.

According to another embodiment, the elastic portion is constituted by a pair of "V" shaped arms extending from a plate. In this case, the elastic portion is constituted by the pair of elastic arms which is able to return to its original shape after deformation.

In this embodiment, the support portion is advantageously constituted by the ends of said arms, which are intended to bear axially against the ring segment so as to press the latter against the part (downstream or upstream) of the housing which is normal to the axis of rotation.

The present invention therefore relates to a turbomachine, for example but not necessarily for a helicopter, comprising a housing, a turbine wheel rotatably mounted about an axis in said housing, a ring concentric with the turbine wheel, said ring being composed of at least a first and a second ring segment, said turbomachine further comprising at least the positioning member described above, the latter being fixed to the casing while exerting an axial thrust on at least one of the segments of rings so as to axially press against a portion of the housing.

Preferably, the positioning member has an attachment portion for attachment to the housing, which fastening portion is located near said portion of the housing to overcome the axial expansion of the ring segments.

Preferably, said portion is a downstream portion of the housing.

Advantageously, the positioning member comprises a first arm fixed to the casing, a second elastic arm exerting an axial thrust on the first ring segment and a third elastic arm exerting an axial thrust on the second ring segment, so as to flatten the ring segments axially against a part crankcase. Preferably, the first and second ring segments are contiguous.

Preferably, the turbomachine according to the invention further comprises at least one wafer covering the junction between the first and second contiguous ring segments, the wafer being held radially against the segments by the positioning member.

Preferably, the positioning member comprises an elastic portion constituted by a tongue having a corrugation, the latter coming into radial abutment against the plate to hold it radially against the contiguous ends of the first and second ring segments.

Preferably, the corrugation has a radial flexibility to absorb the vibrations of the wafer. Moreover, this radial flexibility makes it possible to hold the wafer radially against the ends of the segments regardless of the differential pressure existing between the vein and the cavities internal to the casing.

Another advantage of the positioning member is that it absorbs the vibrations of the segments. The positioning member can also, thanks to the corrugated portions, bear radially on the one hand the ring sector or the sealing tongue, and secondly on the housing part or ring support. The contact on these two parts makes it possible to reduce or even cancel the clearance and radial clearance of the ring sectors, thus ensuring controlled radial positioning of the sectors: this is particularly advantageous as regards the control of the turbine games, and therefore of the performances of it.

The invention will be better understood and its advantages will appear better on reading the following description of embodiments given by way of non-limiting examples. The description refers to the accompanying drawings in which:

- Figure 1 is a perspective view of a first embodiment of the positioning member of the turbomachine according to the invention; FIG. 2 is a partial perspective view of a turbine ring, showing two ring segments held together by a positioning member of FIG. 1;

- Figure 3 is a partial axial sectional view of a turbine engine showing the positioning member of Figure 1 when mounted;

FIG. 4 is a perspective view of a second embodiment of the positioning member according to the invention;

- Figure 5 is a partial axial sectional view of a turbomachine in which is mounted the positioning member of Figure 4;

FIG. 6 is a perspective view of a third embodiment of the positioning member of the turbomachine according to the invention; - Figure 7 is a partial axial sectional view of a turbomachine in which is mounted the positioning member of Figure 6;

FIG. 8 is a perspective view of a fourth embodiment of the positioning member of the turbomachine according to the invention; and

FIG. 9 is a view in partial axial section of a turbomachine in which the positioning member of FIG. 8 is mounted.

With the aid of FIGS. 1 to 3, a first embodiment of the invention will firstly be described.

According to the invention, a positioning member 10 is intended to position a ring segment for a turbine with respect to a casing of the turbomachine in which the turbine is rotatably mounted.

As seen in Figure 1, the positioning member 10 has the general shape of the letter "E". Indeed, it comprises a plate 12 from which orthogonally extend a first central arm 14 and second and third arms bearing the references 16 and 18, so that said arms constitute the three branches of the "E". The arms are therefore substantially parallel to each other. Furthermore, the positioning member 10 has a thin thickness relative to its other dimensions. More specifically, each of the arms is in the form of a corrugated tongue.

According to the invention, the positioning member 10 has an attachment portion 20 which, in this embodiment, is constituted by a bore 22 formed at the free end 14a of the first arm 14, that is to say say at the opposite end to the plate 12. Similarly, the free ends of the second and third arms 16, 18 are referenced 16a and 18a. This fixing portion 20 is intended to be fixed to the housing

62 of the turbomachine so as to fix the positioning member 10 to the casing of the turbomachine. This aspect will be described below.

Each of the first, second and third arms 14, 16 and 18 further comprises an elastic portion 24, 26 and 28 forming a spring. Each of these elastic portions 24,26 and 28 is in the form of a wave. In other words, each of the arms 14, 16 and 18 has a succession of folds so as to form the corrugation, it being specified that the folding axes are transverse to said arms.

These corrugations 24, 26, 28 may be deformed in the longitudinal direction of the arms 14,16 and 18 but then tend to resume their original forms. These corrugations 26, 28 of the second and third arms constitute compression springs in that if one tends to bring the free ends of the plate closer together, the undulations thus deformed generate an opposite force, called compression. On the contrary, the corrugation 24 constitutes a tension spring. An interest of this effect will be explained below.

In addition, the positioning member 10 comprises two support portions 30, 32 constituted by the free ends 16 a, 18 a of the second and third arms 16, 18. As seen in Figure 1, the free ends 16a, 18a are bent to form a kind of hook.

Furthermore, preferably, the length of the second and third arms 16, 18 is slightly greater than that of the first arm 14. With FIGS. 2 and 3, the assembly of the positioning member 10 will now be explained. Conventionally, the ring of a turbine consists of a plurality of ring segments adjacently arranged side by side. Figure 2 shows first and second ring segments 50, 50 'end-to-end with their respective ends 50a and 50'a. The geometry of the ring is such that it comprises an axial direction, a radial direction and an azimuthal direction, these three directions being orthogonal to each other. The ring is, as already mentioned, intended to encircle the turbine wheel of the turbomachine.

A first interest of the positioning member 10 is to maintain the ends 50a, 50a to prevent rotation of the ring segments 50, 50 ^* around the axis of the turbine wheel. To do this, each of the ring segments 50, 50 'carries a rib 52, 52' extending in a transverse direction of the ring segment while projecting radially, so that when the positioning member 10 is mounted, the plate 12 extends in the azimuthal direction of the ring segments 50, 50 ', while the first and second arms 14, 16 flank the rib 52 "of one of the ring segments 50" , while the first and third arms 14, 18 of the member 10 flank the rib 52 of the other ring segment 50. As a result, it is understood that the positioning member 10 prevents the azimuth displacement of the ends 50a, 50'a of each ring segment 50 and 50 '. Preferably, each segment 50, 50 'is held at its two azimuthal ends by two members 10.

As can be seen in FIG. 2, the bearing portions 30, 32 of the positioning member 10, that is to say here the free ends 16a and 18a of the second and third arms 16, 18 come to bear. axial against a peripheral edge 51, 51 'of the first and second ring segments 50, 50'. An interest of this assembly will be explained below.

Another advantage of the present invention is better understood with the aid of FIG. 3 which details the mounting of the ring segments 50, 50 ^* and the positioning member in the casing 62 of the turbomachine 60.

As already mentioned above, the ring segments 50, 50 'are arranged around the high-pressure turbine wheel so as to cover the blades 64 of said turbine. The arrows F indicate the direction of flow of the flue gases leaving a combustion chamber disposed upstream of the high pressure turbine.

As can be understood from FIG. 3, the axial ends 50b, 50c of the ring segment 50 have axial swellings 66, 68 intended to cooperate with projections carried by upstream portions 62a and downstream portions 62b of the casing 62. so that the ring segment 50 is held radially in the housing 62. However, the ring segments 50 are mounted in the housing 62 with slight axial play.

Furthermore, it can be seen that the casing 62 and the ring segments 50, 50 'are arranged in such a way that they delimit an annular passage P for the circulation of a cooling fluid around the ring. Orifices 70 are formed in the housing 62 to allow the supply of this cooling fluid in contact with the ring segments to cool them. According to the invention, the positioning member 10 is fixed to the casing 62 by means of the fixing portion 20, for example using a screw-nut or pin-type locking member 72.

When the positioning member 10 is in the mounted position, its arms 14, 16, 18 extend in the axial direction of the turbine wheel, while the plate 12 is housed between the upstream bulge 66 of the ring segment and the housing 62.

Moreover, the point of attachment of the positioning member 10, that is to say here the nut 72 is arranged relative to the downstream projection 62b of the housing 62 so that the corrugations 24, 26, 28 of the member 10 are continuously compressed axially in their longitudinal direction, whereby the free ends 16a and 18a of the second and third arms 16, 18 exert on the peripheral edges 51, 51 'ring segments 50, 50 ', an axial thrust directed downstream. As a result, the ring segments 50, 50 ^* are pressed axially against a downstream portion of the housing which is constituted here by the above-mentioned downstream projection 62b. The contact between the ring segments 50, 50 'and the downstream part of the casing 62b, which takes place along a contact zone with the reference C, makes it possible to seal between the annular passage P and a downstream duct V, whereby the cooling fluid circulating in the annular passage can not flow into this downstream vein V. Another advantage is that the cooling fluid circulating in the annular passage also cools the corrugations 30, 32 which can be made to heat up. This makes it possible to control the service life of the corrugations, by optimizing their operating temperature.

Finally, in this FIG. 3, it can be seen that the positioning member 10, and more precisely the corrugation 24 of the first arm 14, makes it possible to hold a plate 54 radially against the contiguous ends of the first and second ring segments 50, 50 '. This wafer 54 covers the junction 56 defined between the ends 50a and 50'a of the two ring segments so as to improve the seal between the annular passage and the vein in which the blades 64 of the turbine wheel move.

Another advantage of the positioning member 10 is that it axially pushes the ring segment at each of its azimuthal ends, which improves the contact between the ring segment 50 and the downstream portion 62b of the casing 62, and therefore the seal. The support positioning at the ends of the segments 50, 50 'also makes it possible to reduce the risk of jamming of the segments in the grooves of the casing 62. With the aid of FIGS. 4 and 5, a second embodiment of the invention will now be described. a positioning member 110 according to the present invention. In this embodiment, the elements identical to those of the first embodiment bear the same numerical references increased by the value cent. The positioning member 110 is in the form of a single arm 114 constituted by a tongue. Like the first embodiment, the arm or tab 114 has a resilient portion 124 forming a compression spring, this elastic portion being constituted by a corrugation, the latter being made by folding the tab 114 several times.

In addition, the member 110 has an attachment portion 120 constituted by a tab extending orthogonally with respect to a plane in which the first arm 114 extends. This tab 120 will be made for example by folding the tongue 114. To be consistent with the first embodiment, it can be defined that the member 110 has a plate 112 disposed between the tab 120 and the corrugation 124.

Finally, the tongue 114 has a bearing portion 130 formed by the end of the tab opposite the tab 120, which end is bent.

FIG. 5 shows the mounting of the positioning member 110 in the turbomachine 60.

The positioning member 110 is fixed to the casing 110 by the lug 120. To do this, the latter is radially housed between the ring segment 50 and the casing 62.

The tongue 114 extends axially so that the free end 130 of the latter bears against the edge 51 of the ring segment 50. Moreover, the length of the tongue 114 is chosen so that when the The ring is positioned axially against the downstream portion 62b of the housing, the corrugation 124 of the member 110 is compressed axially. It follows that the end 130 of the tongue exerts an axial thrust against the peripheral edge 51 of the ring segment 50, following which the latter is axially pressed against the downstream portion 62b of the housing 62, in the species according to contact zone C.

It will therefore be understood that the positioning member 110 advantageously maintains the ring segment 50 in axial contact with the downstream part 62b of the casing 62. In addition, the corrugation 124 of the member 110 makes it possible to hold the plate 54 radially against the ends of the ring segments.

With the aid of FIGS. 6 and 7, a third embodiment of the invention will be described. In this embodiment, the elements identical to those of the first embodiment carry the same numerical references increased by the value two hundred.

The positioning member 210 according to the third embodiment has the general shape of an "E". As such, it comprises a first central arm 214 forming a non-corrugated straight plate intended to cover the junction between the two ends of the segments. ring. In other words, this positioning member advantageously allows to dispense with a wafer such as that described above since the first arm 214 fulfills precisely the role of said wafer. At one end of the first arm 214 is a plate 212 carrying a fixing portion 220 constituted by a tab similar to that of the second embodiment.

Platen 212 extends second and third arms 216, 218 similar to those of the first embodiment. That is to say, they respectively carry a first elastic portion 226 and a second elastic portion 228 which form corrugations.

Furthermore, the free ends 216a, 218b constitute support portions 230,232 similar to those of the first embodiment. FIG. 7 shows the positioning member 200 when it is mounted in the casing 60. The tab 220 bears axially on the upstream portion 62a of the casing 62, while the free ends 216a and 218b of the second and third arms come into bearing against the peripheral edge 51 of the ring segment 50 so as to axially press against the downstream edge 62b of the housing 62a. To do this, the length of the second and third arms 216, 218 is slightly greater than the distance between the upstream portion 62a of the housing and the edge 51 so that the corrugations 226 and 228 are in compression. As in the first embodiment, this compression of the corrugations generates an axial thrust on the edge 51 of the contiguous ring segments, the downstream of the free ends 216a and 218a so that the ring segments 50, 50 'are plated. axially against the downstream portion 62b of the casing 62.

With the aid of FIGS. 8 and 9, a fourth embodiment of the invention will now be described. The positioning member 310 comprises a plate 312 provided with a bore 314 constituting a fixing portion for attachment to the casing 62.

A pair of V-shaped arms 318, 320 extends in a bent portion 316 of this plate 312. The positioning member 310 is made of a material having a certain rigidity so that each arm 318, 320 constitutes a portion elastic forming compression spring. Indeed, it is understood that if one tries to spread the arms of one another, they exert a restoring force tending to bring the arms back to their original position, at rest. In other words, the arms 318, 320 act as leaf springs. When the positioning member 310 is mounted, as seen in Figure 9, it is fixed to the housing 62 by a nut 322 similar to that of the first embodiment.

Each arm is provided at its end 318a, 320a with a bearing portion in the form of a hook. In this embodiment, the ends 318a, 320a of the pairs of arms 318 and 320 are intended to bear against the peripheral edge 51 so as to come to press the ring segments 50 and 50 'against the downstream portion 62b of the housing 62. In this position, the arms 318, 320 are slightly deformed so as to maintain an axial pressure against the ring segment 50. The position of the attachment point, that is to say the nut or pin 322 , or the length of the arms 318,320 are chosen so as to obtain this effect.

Claims

1. A turbomachine comprising a housing (62), a turbine wheel rotatably mounted about an axis in said housing, a ring concentric with the turbine wheel, said ring being composed of at least a first (50) and a second (50 ') ring segment, said turbomachine being characterized in that it further comprises at least one positioning member (10, 110, 210, 310), having:

- a fixing portion (20, 120, 220, 314) for attachment to the housing (62);

- an elastic portion (24, 26, 28, 124, 226, 228, 318, 320) forming a spring;

a bearing portion (30, 32, 130, 230, 232, 318a, 320a) connected to the elastic portion and intended to bear axially against the ring segment, said positioning member being fixed to the casing while exerting axial thrust on at least one of the ring segments so as to axially press against a portion of the housing.

2. The turbomachine according to claim 1, characterized in that the positioning member comprises at least a first arm (14, 114, 214, 312) carrying the fixing portion (20, 120, 220, 314).

3. Turbomachine according to claim 2, characterized in that the fixing portion (320) is in the form of a tab extending orthogonally with respect to a plane in which the first arm extends.

4. A turbomachine according to claim 2, characterized in that the fixing portion (20, 314) comprises a bore whose axis extends orthogonally with respect to a plane in which extends the first arm (14, 312). .

5. Turbomachine according to any one of claims 1 to 4, characterized in that the elastic portion (24, 26, 28, 124, 226, 228) consists of a corrugated tongue.

6. Turbomachine according to any one of claims 1 to 5, characterized in that the positioning member comprises at least a first arm (14, 214) carrying the fixing portion, and at least one second arm (16). , 216) comprising the elastic portion.

7. A turbomachine according to claim 6, characterized in that the first (14, 214) and second arm (16, 216) are parallel and extend from a plate (12, 212), and in that the fixing portion (20, 220) is located at one end of the first arm opposite the plate, while the bearing portion is at the end of the second arm opposite the plate.

8. A turbomachine according to claim 6 or 7, characterized in that the positioning member further comprises a third arm (18, 218) similar to the second arm (16, 216) extending from the plate (12, 212). ), the first arm extending between the second and third arms.

9. A turbomachine according to any one of claims 6 to 8, characterized in that the first arm (14) further comprises a second elastic portion (24) disposed between the plate (12) and the fixing portion (20).

10. Turbomachine according to any one of claims 6 to 8, characterized in that the first arm (214) forms a plate for covering a junction between two contiguous ring segments (50, 50 ').

11. Turbomachine according to any one of claims 1 to 4, characterized in that the elastic portion (318, 320) is constituted by a pair of arms shaped "V" extending from a plate (312).

12. A turbomachine according to claim 11, characterized in that the bearing portion is constituted by the ends (318a, 320a) of said arms.

13. A turbomachine according to claim 1, characterized in that the positioning member comprises a portion (20, 120, 220, 314) fixed to the housing, a second resilient arm (16, 216, 318) exerting an axial thrust on the first ring segment (50) and a third resilient arm (18, 218, 310) exerting an axial thrust on the second ring segment (50 '), so as to press the ring segments (50, 50') ) axially against a portion (62b) of the housing (62).

14. Turbomachine according to any one of claims 1 to 13, characterized in that it further comprises at least one plate (54, 214) covering the junction between the first and second ring segments (50, 50 '), the wafer being held radially against the ring segments by the positioning member (10, 110, 210).