EP3176386B1 - Inner shroud assembly, corresponding inner shroud, inner casing and turbomachine - Google Patents

Description

The invention relates to an inner ring system for an inlet guide vane ring of a turbomachine. The invention further relates to an inner ring and an intermediate housing for such an inner ring system and to a turbo machine with such an inner ring system.

The disclosure documents U.S. 3,314,654 A , EP 2 261 467 A2 , EP 2 472 066 A1 and WO 2014/046965 A1 disclose inner ring systems for an adjustable guide vane ring in an axial gas turbine. The inner ring systems each comprise two or more ring segments, which together serve to support radial end regions of guide vanes and are screwed together.

From the disclosure documents WO 2015/149732 A2 and DE 10 2014 205986 A1 Axially split inner ring systems for adjustable guide vane rings are known, the inner ring systems bearing brush seals.

From the EP 1 319 844 B1 an inner ring or bearing ring for a guide vane ring of a turbomachine is known. The inner ring is axially divided into a first and a second ring segment, which in the assembled state jointly form recesses for mounting the blade roots of the guide vanes of the guide vane ring. For this purpose, the inner ring has a large number of axial mounting bores or openings, via which the two ring segments are screwed together. The inner ring is assembled in a second stage of a compressor of the turbomachine, so that the inner ring is carried by the guide vane ring.

A disadvantage of the known inner ring is the fact that it has a comparatively low mechanical stability in the assembled state in a turbomachine and can only absorb loads to a very limited extent. The inner ring is therefore not particularly suitable for an inlet guide vane ring, that is to say for one first stage of a compressor or a turbine. The term compressor or turbine also means, in particular, a compressor module or a turbine module of the turbomachine. Under certain circumstances, particularly high loads can occur here, for example from bird strikes. A compressor module can be, for example, a low-pressure compressor, medium-pressure compressor or high-pressure compressor. The same applies to the turbine module; a low-pressure turbine or medium-pressure turbine or high-pressure turbine can be meant. Due to the comparatively low mechanical stability, the relative positioning of the ring segments of the inner ring to one another changes during the operation of the assigned turbomachine, which on the one hand is associated with deteriorated aerodynamic properties and on the other hand there is increased wear in the area of the mounted blade roots. This high level of wear leads to correspondingly high maintenance costs.

The object of the present invention is to specify an inner ring system for a first stage of a compressor or a turbine which enables improved aerodynamic properties and a reduction in maintenance costs. Further objects of the invention consist in providing an inner ring and an intermediate housing for such an inner ring system as well as a turbomachine with such an inner ring system.

The objects are achieved according to the invention by an inner ring system with the features of claim 1, an inner ring according to claim 11 and an intermediate housing according to claim 12 for such an inner ring system and by a turbo machine according to claim 13. Advantageous refinements with expedient refinements of the invention are specified in the respective subclaims, with advantageous refinements of each aspect of the invention being regarded as advantageous refinements of the other respective aspects of the invention.

A first aspect of the invention relates to an inner ring system for an inlet guide vane ring of a turbomachine. The inner ring system comprises an intermediate housing for absorbing structural loads and an inner ring which is axially divided into a first and a second ring segment, which together form recesses for supporting radially inner end areas of guide vanes of the inlet guide vane ring, at least the second ring segment being fixed to the intermediate housing by means of screw connections is. As a result, the inner ring system has a particularly high mechanical stability, since loads occurring during the operation of an associated turbomachine, which are transmitted to the ring segments of the inner ring via guide vanes mounted in the recesses, can be passed on to the intermediate housing, which, as a machine-fixed element, the structural loads can absorb and distribute much better than is possible with inner rings that are carried exclusively by a guide vane ring. The screw connection of the inner ring to the intermediate housing also results in lower relative movements during operation of the associated turbomachine due to tolerances or thermal movements between the two ring segments. This leads to a better blade positioning and thus better aerodynamic properties that cannot be achieved without screw connections or only with latches or the like. The more precise and less torsion-free positioning of the guide vanes also reduces wear in the area of the guide vane roots, as a result of which a corresponding reduction in maintenance costs can be achieved. The screw connection of the inner ring to the intermediate housing, which is also referred to as IMC (intermediate casing), also reduces or eliminates axial deflections, for example during a bird strike. According to the invention, the first ring segment is sealed against the intermediate housing via a radially outer and / or via a radially inner sealing element. This improves the aerodynamic properties of the inner ring system and prevents flow losses during the operation of the associated turbomachine, which results in corresponding increases in efficiency. The first and second ring segments are preferably designed by a corresponding radial seat in such a way that the first ring segment only requires one sealing element for radially inner or radially outer sealing, since this saves additional manufacturing and assembly costs.

Another advantage of the design according to the invention with the two-part construction of the inner ring is the possibility of joint machining of the two ring segments. For example, the recesses for mounting the guide vane roots can be drilled together. For this purpose, the two ring segments can be clamped or fixed to one another with a corresponding tool, after which the recesses can be drilled with corresponding precision. As a result, the recesses can be positioned more precisely, which together with the screw connection of the inner ring to the intermediate housing leads to additionally reduced relative movements due to tolerances or thermal movements during operation between the two ring segments. In this way, the blade positioning and thus its aerodynamic properties can also be improved.

In an advantageous embodiment of the invention it is provided that the first ring segment is to be arranged upstream with respect to a primary flow of the turbomachine and the second ring segment is to be arranged downstream with respect to the primary flow. In other words, the first and the second ring segment are axially separated and are to be arranged one after the other in the flow direction. This facilitates the assembly and disassembly of the ring segments. It can in particular it can be provided that the first ring segment is arranged directly on the intermediate housing, while the second ring segment in turn rests downstream on the first ring segment.

Further advantages result from the fact that the first and the second ring segment have a plurality of pairs of mutually aligned assembly openings, through each of which a screw of the screw connections is guided to the intermediate housing. As a result, both the first and the second ring segment can be screwed together with the intermediate housing, which leads to a particularly high mechanical stability. In addition, the common screw connection also improves correct relative alignment of the two ring segments to one another.

Alternatively, it is provided in a further advantageous embodiment of the invention that the first ring segment is floatingly mounted on the second ring segment and on the intermediate housing and the second ring segment is screwed to the intermediate housing and / or that the first ring segment on the second ring segment, on the intermediate housing and in the Recesses to be arranged bearing elements of the guide vanes is to be supported. In other words, in this embodiment, only the second ring segment is screwed to the intermediate housing, while the first ring segment is floatingly mounted or is only fixed indirectly via the second ring segment to the intermediate housing or is clamped to the intermediate housing. This enables a particularly compact design for geometrically small steps or for cramped installation situations.

In a further embodiment of the invention it is provided that the first ring segment comprises a groove in which a projection of the second ring segment is arranged. This simplifies the relative positioning of the two ring segments to one another during assembly and additionally increases the mechanical stability of the inner ring in the assembled state. The projection is preferably not positively received in the groove in order to allow thermally and / or mechanically induced relative movements, volume changes, etc. of the two ring segments.

Further advantages result because the first ring segment has a radially outer and / or a radially inner O-ring as a sealing element against the intermediate housing and / or via a radially outer and / or a radially inner sealing element, in particular an O-ring, is sealed against the second ring segment. This improves the aerodynamic properties of the inner ring system and prevents flow losses during the operation of the associated turbomachine, which results in corresponding increases in efficiency. The first and second ring segments are preferably configured by a corresponding radial seat in such a way that the first

Ring segment only requires one sealing element for radially inner or radially outer sealing, since this saves additional manufacturing and assembly costs.

In a further advantageous embodiment of the invention it is provided that the inner ring is screwed to the intermediate housing from a downstream side and / or from an upstream side. This allows a high degree of structural flexibility. Preferably, at least the second ring segment of the inner ring is only screwed from the downstream side, since this allows an advantageous and inexpensive assembly and disassembly of the inner ring without complete disassembly of the entire inner ring system or the bearing housing.

In a further advantageous embodiment of the invention, at least one of the ring segments comprises at least one receptacle for the arrangement of a brush seal. In other words, at least one and preferably at least the second ring segment is designed to carry a brush seal, wherein the brush seal can be fastened or fixed in the receptacle, for example by means of mechanical clamping. With the aid of a brush seal held on at least one of the ring segments, a particularly compact, light and powerful seal of the inner ring system with respect to a rotor of the associated turbomachine can be realized. In principle, all suitable types can be provided as brush seals. For example, a suitable brush seal comprises a brush seal housing, which consists of a support plate and a cover plate, which are connected to one another and together encompass at least one brush head of the brush seal system in a U-shape and secure it against falling out of the brush seal housing. The cover plate or the area of the two-part brush seal housing located upstream in the flow direction is primarily intended to prevent disruptive flow influences on a brush package protruding from the brush head and protruding from the brush seal housing, while the support plate of the brush seal housing located downstream, viewed in the flow direction, serves as a support element that prevents sagging of the brush pack in the axial direction of the aircraft engine due to the pressure difference across the brush seal housing.

In a further advantageous embodiment of the invention it is provided that the first and / or second ring segment comprises means for axially supporting the brush seal in the region of the receptacle. This allows a stop for a simple design Element of the brush seal, for example for the brush seal housing, which on the one hand facilitates the assembly of the brush seal and on the other hand additionally increases the load capacity of the brush seal.

In a further advantageous embodiment of the invention, the first and the second ring segment are aligned relative to one another and / or relative to a circumferential direction of the intermediate housing via at least one dowel pin. This ensures a further improvement in the positioning accuracy of the ring segments in a structurally simple manner.

A second aspect of the invention relates to an inner ring for an inner ring system according to the first aspect of the invention. According to the invention, the inner ring is axially divided into a first and a second ring segment which, when assembled, jointly form recesses for supporting radially inner end areas of guide vanes of the inlet guide vane ring, with at least the second ring segment having mounting openings for screwing to the intermediate housing of the inner ring system. As a result, the inner ring enables improved aerodynamic properties and a reduction in the maintenance costs of the inner ring system. In principle, it can also be provided that only the second ring segment comprises mounting openings or that both the first and the second ring segment have mounting openings for joint screwing to the intermediate housing. The first ring segment has a radially outer and / or a radially inner sealing element for sealing against the intermediate housing. This improves the aerodynamic properties of the inner ring system and prevents flow losses during the operation of the associated turbomachine, which results in corresponding increases in efficiency. The first and second ring segments are preferably designed by a corresponding radial seat in such a way that the first ring segment only requires one sealing element for radially inner or radially outer sealing, since this saves additional manufacturing and assembly costs. Further features and their advantages can be found in the descriptions of the first aspect of the invention, with advantageous configurations of the first aspect of the invention being regarded as advantageous configurations of the second aspect of the invention. Conversely, advantageous configurations of the second aspect of the invention are also to be regarded as advantageous configurations of the first aspect of the invention.

A third aspect of the invention relates to an intermediate housing with an inner ring system according to the first aspect of the invention. It is provided that the intermediate housing includes assembly openings for screwing at least the second ring segment of the inner ring of the inner ring system. As a result, the intermediate housing enables improved aerodynamic properties and a reduction in the maintenance costs of the inner ring system. Further features and their advantages can be found in the descriptions of the first and the The second aspect of the invention can be seen, with advantageous configurations of the first and second aspects of the invention being regarded as advantageous configurations of the third aspect of the invention. Conversely, advantageous configurations of the third aspect of the invention are also to be regarded as advantageous configurations of the first and second aspects of the invention.

A fourth aspect of the invention relates to a turbomachine, in particular an aircraft engine. According to the invention, the turbomachine comprises an inner ring system according to the first aspect of the invention and an inlet guide vane ring, which has a plurality of guide vanes, each comprising a radially outer and a radially inner end area with respect to a ring longitudinal axis, the radially inner end areas of the guide blades in the joint through the first and the second ring segment of the inner ring formed recesses are arranged. As a result, the turbomachine has improved aerodynamic properties and can be maintained at lower costs. The guide vanes of the inlet guide vane ring are also referred to as IGV (inlet guide vanes), while their radially inner end regions can also be referred to as blade roots. Further features and their advantages can be found in the descriptions of the first, second and third aspects of the invention, with advantageous configurations of the first, second and third aspects of the invention being regarded as advantageous configurations of the fourth aspect of the invention and vice versa.

In an advantageous embodiment of the invention it is provided that the guide vanes are adjustable and / or that the radially inner end regions of the guide vanes are held in the recesses via bearing bushes. Due to the screw connection of the inner ring to the intermediate housing, the guide vanes, which are designed as adjustable vanes, are mechanically particularly stable in the area of their vane root (e.g. inner journal or vane disk), which, in addition to improving the mechanical and aerodynamic properties, also significantly reduces the vibration load on the guide vanes. The bearing bushes can be clamped in the recesses, for example. With the help of bearing bushes, the storage, tightness and assembly of the guide vanes can advantageously be improved. Due to the lower relative movements of the ring segments due to the screw connection of the inner ring, the bearing bushes are also subject to considerably less wear.

Further advantages result in that the inner ring system and the inlet guide vane ring are part of a low-pressure compressor stage and / or a medium-pressure compressor stage and / or a high-pressure compressor stage and / or a high-pressure turbine stage and / or a medium-pressure turbine stage and / or a low-pressure turbine stage of the flow machine. In other words, the inner ring system is part of a first stage of an LP, MD and / or HP compressor or a LP, MD and / or HP turbine of the turbo machine. In this way, the advantageous properties of the inner ring system can be implemented for differently constructed types of turbomachines or at different points within the turbomachine.

Fig. 1

einen schematischen Ausschnitt einer erfindungsgemäßen Strömungsmaschine im Bereich einer ersten Stufe eines Verdichters;

Fig. 2

einen schematischen Ausschnitt einer alternativen Ausführungsform der erfindungsgemäßen Strömungsmaschine im Bereich einer ersten Stufe eines Verdichters; und

Fig. 3

einen schematischen Ausschnitt einer weiteren alternativen Ausführungsform der erfindungsgemäßen Strömungsmaschine im Bereich einer ersten Stufe eines Verdichters.

Further features of the invention emerge from the claims and the exemplary embodiments. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the exemplary embodiments and / or shown alone, can be used not only in the specified combination, but also in other combinations or on their own, without falling within the scope of the invention leave. Thus, embodiments of the invention are also to be regarded as encompassed and disclosed, which are not explicitly shown and explained in the exemplary embodiments, but which emerge and can be generated by separate combinations of features from the explained embodiments. Designs and combinations of features are also to be regarded as disclosed, which therefore do not have all the features of an originally formulated independent claim. It shows:

Fig. 1

a schematic section of a turbomachine according to the invention in the area of a first stage of a compressor;

Fig. 2

a schematic section of an alternative embodiment of the flow machine according to the invention in the area of a first stage of a compressor; and

Fig. 3

a schematic section of a further alternative embodiment of the turbo machine according to the invention in the area of a first stage of a compressor.

Fig. 1 shows a schematic section of a turbo machine 10 according to the invention in the area of a first stage of a compressor 12. The turbo machine 10 is designed as an aircraft engine. The compressor 12, which can be, for example, a single-stage or multi-stage low, medium or high pressure compressor, comprises as a first stage an inlet guide vane ring 14, which has a plurality of guide vanes 16 (inlet guide vanes, IGV), which are referred to on a ring longitudinal axis A each comprise a radially outer end region (not shown) and a radially inner end region 18, wherein the end region 18 can also be referred to as the blade root. The radially inner end regions 18 of the guide vanes 16 are arranged in recesses 22 together with the respective bearing bushes 20. The recesses 22 are formed jointly by a first ring segment 24a and a second ring segment 24b of an axially divided inner ring 26. In the present exemplary embodiment, the first ring segment 24a is arranged upstream with respect to a primary flow of the turbomachine 10 and the second ring segment 24b is arranged downstream with respect to the primary flow. To improve the mechanical and aerodynamic properties, the inner ring 26 is screwed to an intermediate housing 28 (IMC) for absorbing structural loads. For this purpose, in the present embodiment, the first ring segment 24a and the second ring segment 24b have several pairs of aligned mounting openings 30a, 30b distributed over the circumference of the intermediate housing 28, through which a screw 32 is guided to the intermediate housing 28 and in a corresponding one, in this case with a thread provided mounting opening 30c of the intermediate housing 28 is screwed. Alternatively, other fastening variants such as lock nuts or the like can also be provided. In the present case, the screw connection takes place from the downstream side of the inner ring 26. This advantageously enables the ring segments 24a, 24b to be dismantled without completely dismantling the entire bearing structure.

It can be seen that the first ring segment 24a in the illustrated embodiment comprises a groove 34 in which a projection 36 of the second ring segment 24b is arranged with play. This restricts the relative mobility of the second ring segment 24b with respect to the first ring segment 24a, which increases the mechanical stability and facilitates the assembly of the inner ring 26. The first ring segment 24a is against the intermediate housing 28 via a radially outer sealing element 38, in the present case designed as an O-ring sealed. A radially lower seal can be omitted, since the seal for the air system takes place via the radial seat between the front and rear ring segments 24a, 24b. The omission of a seal leads to lower costs, both in the production and in the maintenance of the turbomachine 10.

The second ring segment 24b further comprises in the area of its downstream end a receptacle 40 in which a brush seal 42 is mounted, by means of which a seal of the inner ring 26 with respect to a rotor 44 of the compressor 12 is achieved. The brush seal 42 comprises a brush seal housing 46 which is fixed in the receptacle 40 via two clamping plates 48. Furthermore, the second ring segment 24b comprises a stop 50 in the region of the receptacle 40 for axially supporting the brush seal 42.

For relative alignment, the first and second ring segments 24a, 24b can be aligned relative to one another or relative to a circumferential direction of the intermediate housing 28 via at least one dowel pin (not shown).

The more precise positioning of the mounting bores 30a-c and thus also the bearing bushes 20 reduces bush wear. Less wear and tear also means a reduction in maintenance costs. The more precise positioning and less wear of the bushing also leads to an improved positioning of the guide vanes 16 during operation and thus to improved aerodynamics.

Fig. 2 shows a schematic section of an alternative embodiment of the turbo machine 10 according to the invention in the area of a first stage of a compressor 12. The basic structure corresponds to that in connection with FIG Fig. 1 discussed. In contrast to the previous exemplary embodiment, the first ring segment 24a has no groove 34 or depression. Accordingly, the second ring segment 24b also has no projection 36.

Fig. 3 shows a schematic section of a further alternative embodiment of the turbo machine 10 according to the invention in the area of a first stage of a compressor 12. It can be seen that the inner ring 26 in the present example only extends over the second Ring segment 24b is screwed to the intermediate housing 28. In contrast, the first ring segment 24a is floatingly mounted and is secured in position via the screwed-on second ring segment 24b, the bearing bush 20, the blade root 18 and the intermediate housing 28. In contrast to the previous exemplary embodiments, the second ring segment 24a is screwed to the intermediate housing 28 from the upstream side of the inner ring 26, so that the second ring segment 24b has a corresponding internal thread in its assembly opening 30b. For sealing, the first ring segment 24a has a radially upper and a radially lower sealing element 38, each of which is designed as an O-ring. The basically optional stop 50 is shown in dashed lines.

List of reference symbols:

10

Turbo machine

12

compressor

14th

Inlet guide vane ring

16

Guide vanes

18th

End area

20th

Bearing bush

22nd

Recesses

24a

Ring segment

24b

Ring segment

26th

Inner ring

28

Intermediate housing

30a

Assembly opening

30b

Assembly opening

30c

Assembly opening

32

screw

34

Groove

36

head Start

38

Sealing element

40

admission

42

Brush seal

44

rotor

46

Brush seal housing

48

Clamping plates

50

attack

Claims (15)

1. Inner ring system for an inlet guide vane ring (14) of a turbomachine (10), comprising:

   - an intermediate housing (28) for receiving structural loads; and

   - an inner ring (26) which is axially divided into a first ring segment and a second ring segment (24a, 24b) which togetherform recesses (22) for mounting radially inner end regions (18) of guide vanes (16) of the inlet guide vane ring (14),

   at least the second ring segment (24b) being fixed to the intermediate housing (28) by means of screw connections, characterized in that the first ring segment (24a) is sealed with respect to the intermediate housing (28) by a radially outer and/or a radially inner sealing element (38).
2. Inner ring system according to claim 1, characterized in that the first ring segment (24a) is to be arranged upstream with respect to a primary flow of the turbomachine, and the second ring segment (24b) is to be arranged downstream with respect to the primary flow.
3. Inner ring system according to either claim 1 or claim 2, characterized in that the first ring segment and the second ring segment (24a, 24b) have a plurality of pairs of mutually aligned assembly openings (30a, 30b), through each of which a screw (32) of the screw connections is guided to the intermediate housing (28).
4. Inner ring system according to either claim 1 or claim 2, characterized in that the first ring segment (24a) is floatingly mounted on the second ring segment (24b) and on the intermediate housing (28), and the second ring segment (24b) is screwed to the intermediate housing (28), and/or in that the first ring segment (24a) is to be supported on the second ring segment (24b), on the intermediate housing (28) and on bearing elements (20) of the guide vanes (16) that are to be arranged in the recesses (22).
5. Inner ring system according to any of claims 1 to 4, characterized in that the first ring segment (24a) comprises a groove (34) in which a projection (36) of the second ring segment (24b) is arranged.
6. Inner ring system according to any of claims 1 to 5, characterized in that the first ring segment (24a) is sealed with respect to the intermediate housing (28) by a radially outer and/or a radially inner O-ring as a sealing element (38) and/oris sealed with respect to the second ring segment (24b) by a radially outer and/or a radially inner sealing element (38), in particularan O-ring.
7. Inner ring system according to any of claims 1 to 6, characterized in that the inner ring (26) is screwed to the intermediate housing (28) from a downstream side and/or from an upstream side.
8. Inner ring system according to any of claims 1 to 7, characterized in that the at least one of the ring segments (24b) comprises at least one receptacle (40) for the arrangement of a brush seal (42).
9. Inner ring system according to claim 8, characterized in that the first and/or second ring segment (24a, 24b) comprises means (50) for axially supporting the brush seal (42) in the region of the receptacle (40).
10. Inner ring system according to any of claims 1 to 9, characterized in that the first ring segment and the second ring segment (24a, 24b) are oriented relative to one another and/or relative to a circumferential direction of the intermediate housing (28) by at least one alignment pin.
11. Inner ring (26) for an inner ring system according to any of claims 1 to 10, which inner ring is axially divided into a first ring segment and a second ring segment (24a, 24b) which, in the assembled state, togetherform recesses (22) for mounting radially inner end regions (18) of guide vanes (16) of the inlet guide vane ring (14), wherein at least the second ring segment (24b) has assembly openings (30b) for the screw connection to the intermediate housing (28) of the inner ring system, wherein the first ring segment (24a) has a radially outer and/ora radially inner sealing element (38) for sealing with respect to the intermediate housing (28).
12. Intermediate housing (28) comprising an inner ring system according to any of claims 1 to 10, wherein the intermediate housing (28) comprises assembly openings (30c) for screwing at least the second ring segment (24b) of the inner ring (26) of the inner ring system.
13. Turbomachine (10), in particular an aircraft engine, comprising

    - an inner ring system according to any of claims 1 to 10; and

    - an inlet guide vane ring (14) which has a plurality of guide vanes (16) which, with respect to a ring longitudinal axis (A), each comprise a radially outer and a radially inner end region (18), wherein the radially inner end regions (18) of the guide vanes (16) are arranged in the recesses (22) together formed by the first ring segment and the second ring segment (24a, 24b) of the inner ring (26).
14. Turbomachine (10) according to claim 13, characterized in that the guide vanes (16) are adjustable and/or in that the radially inner end regions (18) of the guide vanes (16) are held in the recesses (22) by bearing bushes (20).
15. Turbomachine (10) according to eitherclaim 13 or claim 14, characterized in that the inner ring system and the inlet guide vane ring (14) are part of a low-pressure compressor stage and/or a medium-pressure compressor stage and/ora high-pressure compressor stage and/ora high-pressure turbine stage and/or a medium-pressure turbine stage and/or a low-pressure turbine stage of the turbomachine (10).

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