EP3176384B1 - Inner shroud, corresponding inner shroud sector, vane assembly and turbomachine - Google Patents

Description

The invention relates to an inner ring for a vane ring, an inner ring sector for an inner ring, a vane ring with an inner ring and a plurality of vanes, and a turbomachine with a vane ring.

Flow machines, such as aircraft engines and stationary gas turbines, often have at least one row of guide vanes on the compressor side with a large number of guide vanes in order to set optimal operating conditions. The row of guide vanes forms a so-called guide vane ring with an inner ring. The guide vanes can preferably be pivoted about their longitudinal axis.

The adjustable guide vanes can be actuated by means of adjusting pins of the guide vanes mounted radially on the outside, with the adjusting pins being able to interact with a corresponding adjusting device on the outer housing. A seal carrier is preferably guided on the inner ring, which seal carrier is provided with sealing elements or inlet linings, which are opposite sealing ribs on the rotor side.

The inner ring preferably has a plurality of receptacles extending in the radial direction, in each of which a guide vane plate of a guide vane is or can be inserted. The radially inner end of a guide vane is stabilized by such a guide vane plate arranged in the receptacle. The axis of rotation of the adjustable guide vane is perpendicular to the central axis of the guide vane ring or its inner ring. The vane plate may have a journal on its radially inner side, and the receptacle may be adapted to receive this journal together with an associated bushing.

The receptacles in the inner ring are separated from one another in the circumferential direction by respective partitions running in the axial direction. During the manufacture of the inner ring and during operation of the vane ring, there is a risk that such a dividing wall will partially give way and will thus be pressed into an adjacent receptacle, which as a result no longer has its exact shape; this can be a scheduled recording of a Guide vane plate and/or pivoting of the guide vane, or at least impede it. The partition wall can also be bent in the direction of an adjacent receptacle during operation and thus impair the pivotability of a guide vane inserted therein.

In order to reduce the risk of such a deformation of the receptacles, conventional inner rings are therefore manufactured with a minimum wall thickness for the partition walls, which they must have at their thinnest points.

With a given circumference of the inner ring, the number of seats for guide vane discs (and thus the number of guide vanes that can be mounted) is determined by the given vane disc sizes and the minimum wall thickness to be observed. These parameters therefore have a limiting effect on the design of the turbomachine with a large number of pivotable guide vanes or large guide vane disks. However, such a design and/or a minimum size of the vane plates is often advantageous in terms of aerodynamics and/or structural mechanics.

The pamphlet WO 2014/078 121 A1 discloses an arrangement in which the receptacles are not separated from one another by partition walls, but rather the recesses for the vane plates are arranged in a merging manner on a radially outer inner ring surface.

This has the disadvantage of increased leakage between and through the vane plate seats. In addition, centering of the vane plates can be unstable in such an arrangement.

The pamphlet EP 1 967 718 A2 discloses an inner ring for a vane ring of a turbomachine according to the prior art.

The object of the present invention is to provide an inner ring or an inner ring sector or a ring of guide vanes or a turbomachine with stable centering and low leakage, the ring of guide vanes having a design that is aerodynamically and/or mechanically improved for a given circumference.

The object is achieved by an inner ring according to claim 1, by an inner ring sector according to claim 7, by a vane ring according to claim 8 and by a turbomachine according to claim 10. Advantageous embodiments are disclosed in the dependent claims, the description and the figures.

An inner ring according to the invention for a vane ring of a turbomachine has a radially outer inner ring surface and a plurality of receptacles for each vane disk of a (preferably pivotable) vane; Unless otherwise stated, the designations “radial” and “axial” in this document always refer to a central geometric axis of the inner ring, which is not always specifically formulated for better legibility; the same applies to the term "direction of rotation". The receptacles each have an opening in the radially outer surface of the inner ring and (at least) one bottom surface lying radially opposite the opening. At least two of the receptacles are separated from one another (in the direction of rotation) by a partition and connected to one another by an opening in a region of the base surfaces of the receptacles; the at least two receptacles are preferably arranged adjacently in the direction of rotation of the inner ring.

The at least one bottom surface of a receptacle of an inner ring according to the invention is therefore radially further inwards than the radially outer surface of the inner ring and faces radially through the opening an area surrounding the inner ring. If the vane plate is not used, the bottom surface is visible from the outside when viewed radially (inwards). In particular, such a bottom surface can form a stop for a guide vane plate to be inserted into the receptacle in the radial direction.

The receptacles can each be set up to accommodate a guide vane disk to be inserted with a bearing journal optionally arranged thereon, possibly also a bearing bushing for such a bearing journal. The at least one bottom surface can form a stop surface for the bearing journal or for a bearing bushing for the bearing journal to be inserted radially into the receptacle, or another can be delimited in the at least one bottom surface and/or (at least partially) by it Opening of a depression can be formed, which can be set up, for example, to receive a bearing journal of the vane plate.

An inner ring sector according to the invention (which can be designed as a half, third or quarter ring, for example) is set up to be assembled with at least one other inner ring sector to form an inner ring according to one of the embodiments disclosed in this document. It comprises at least two of the receptacles of the (combined according to the invention) inner ring which are separated from one another by a partition and are connected to one another in a region of their bottom surface by an opening.

A ring of guide vanes according to the invention for a turbomachine has an inner ring according to one of the embodiments disclosed in this document and a plurality of guide vanes inserted into the receptacles.

A turbomachine according to the invention comprises a vane ring according to the invention.

An inner ring according to the invention, an inner ring sector according to the invention, a ring of guide vanes according to the invention and a turbomachine according to the invention each enable safe, stable centering of the guide vane plates in their respective receptacle with reduced leakage.

In addition, they advantageously enable an arrangement of guide vanes in which the distance between adjacent guide vane disks or bearing bushes is minimized and at the same time the risk of deformation of a receptacle can be avoided: In particular, when two adjacent receptacles have circular-cylindrical sections, they converge radially inward to. In the area of their bottom surfaces, they therefore have a very small distance from one another. According to the present invention, no minimum distance needs to be maintained in this area in order to prevent a partition wall that is too thin from being unfavorably deformed in this area: According to the invention, in this narrowest area there is an opening between the receptacles, so that a partition wall that could deform does not exist there. On the other hand, radially further outwards, where the circular-cylindrical sections of the receptacles are further apart, the receptacles are separated from one another by a partition; this enables a safe and stable storage of guide vanes or bearing bushes for guide vanes.

In particular, such an inner ring enables an improvement in the efficiency and durability of a turbomachine.

Preferably, the at least two receptacles each comprise an essentially circular-cylindrical section (e.g. a circular-cylindrical bore) in the inner ring, which runs radially in relation to the inner ring. Such receptacles can accommodate correspondingly shaped guide vane disks or bearing bushes with a circular-cylindrical section, which enables the guide vanes to be mounted and pivoted in a particularly secure and stable manner.

According to an advantageous embodiment, the at least two receptacles (in the circumferential direction) along the radially outer inner ring surface (at its or one of its narrowest point(s)) are at a distance of at most 3 mm, more preferably at most 2 mm, from one another.

In this way, a large number of guide vanes of a respectively advantageous guide vane plate size can be used in the receptacles in the inner ring, and the partition wall is strong enough not to be deformed.

An embodiment variant is advantageous in which the partition wall between the at least two receptacles extends radially from the radially outer surface of the inner ring by at least 2 mm, more preferably at least 3 mm, into the inner ring.

According to an advantageous embodiment, the opening between the at least two receptacles has a radial height of at least 2 mm, more preferably at least 3 mm; the radial height is to be measured radially outwards starting from the bottom surface (or from one of the bottom surfaces if there are several).

For example, in the case of receptacles with a circular-cylindrical section and therefore a partition wall that tapers from the outside inwards, a minimum thickness of the partition wall is ensured by the inward radial extension of the partition wall (and thus its taper) being limited by the opening.

In the axial direction (relative to a central axis of the inner ring), the opening preferably has a width of at least 3 mm, more preferably at least 4 mm. In this way, an unfavorably small dividing wall thickness on the side of a center of the opening (e.g. in the narrowest area between two receptacles) can be avoided.

According to the invention, the opening in the circumferential direction (relative to the inner ring) has an essentially triangular, circular segment, round or pointed arch cross section.

The breakthrough can thus be optimized depending on a shape of the inner ring, for example its size and/or its surface design. A triangular cross-section can be particularly easy to produce, for example, in the case of an axially divided inner ring, because for this purpose the dividing wall only has to be beveled on the partial rings to be assembled; The same applies to a pointed arch cross section. In the case of an axially undivided inner ring, the production of a circular section or an arcuate cross-section can be associated with less effort. In addition, the avoidance of a central peak associated with such cross-sections can advantageously reduce leakage in this area.

According to an advantageous embodiment, an inner ring according to the invention comprises two inner ring parts (e.g. partial rings) assembled in the axial direction, which each have an edge in the axial direction, which delimits the plurality of receptacles in sections. The sockets are thus arranged between the inner ring parts which together form at least part of an enclosure for each socket.

Such two-part inner rings are particularly useful for inserting the guide vanes and can also be produced with relatively little effort. In particular, they simplify the formation of the opening in a partition wall inner ring according to the invention, because this is particularly easily accessible in not yet assembled inner ring parts.

Of the two inner ring parts, a first (e.g. rear in the main flow direction) inner ring part can have, on a side facing the second (e.g. front in the main flow direction) inner ring part, an axially extending projection with a surface that preferably forms the bottom surface for the receptacles, the Projection on an outer edge engages in an annular, axially extending groove of the second inner ring part.

The at least two receptacles of an inner ring according to the invention that are connected by the opening are preferably designed in such a way that at least two of the guide vanes used in the area of the opening (e.g. in the area of the bottom surfaces) have a distance (at their narrowest point or at a narrowest point) of a maximum of 0.5 mm (in the direction of rotation) have. It is advantageous if the guide vanes are used without contact in the area mentioned, for example at a distance of at least 0.1 mm.

Correspondingly, at least two guide vanes (or their associated guide vane plates) of a guide vane ring according to the invention inserted into corresponding receptacles preferably have a maximum spacing of 0.5 mm in the area of the breakthrough, more preferably in a range between 0.1 mm and 0.5 mm.

Thus, according to the invention, the guide vanes can be arranged close together, so that a large number of guide vanes with a suitable guide vane plate size can be used in the inner ring. Said advantageous minimum spacing of 0.1mm prevents contact of the vane discs which could otherwise impede insertion and/or impede pivoting of the vanes during use.

In embodiments in which the guide vanes have bearing journals which are inserted into bearing bushes and are or are used together with these in the receptacles, the bearing bushes in the area of the breakthrough preferably have a maximum spacing (in the circumferential direction) of 0.5 mm. preferably in one area between 0.1mm to 0.5mm. Alternatively or additionally, the radial height of the opening in embodiments with (possibly provided) bearing bushes is preferably at most as large as a jacket height or thickness of the bearing bushes (i.e. at most as large as the extension of the bearing bushes used in - in relation to the inner ring - in the radial direction ). Limiting the height of the breakthrough in this way reduces leakage at the radially outer side of the bearing bushes.

Preferred exemplary embodiments of the invention are explained in more detail below with reference to drawings. It goes without saying that individual elements and components can also be combined differently than shown. Reference symbols for elements that correspond to one another are used throughout the figures and may not be described anew for each figure.

Figur 1:

einen Abschnitt eines Leitschaufelkranzes in perspektivischer Darstellung;

Figur 2:

einen Abschnitt eines exemplarischen erfindungsgemäßen Innenrings mit eingesetzten Lagerbuchsen in einer Schnittdarstellung;

Figur 3:

einen Abschnitt eines Innenrings gemäß einer exemplarischen Ausführungsform der vorliegenden Erfindung;

Figur 4.

einen Abschnitt eines hinteren Teils eines beispielhaften erfindungsgemäßen Innenrings;

Figuren 5a, 5b:

je eine Explosionsdarstellung eines exemplarischen erfindungsgemäßen Innenrings mit Lagerbuchse und Leitschaufel.

They show schematically:

Figure 1:

a section of a vane ring in a perspective view;

Figure 2:

a section of an exemplary inner ring according to the invention with inserted bearing bushes in a sectional view;

Figure 3:

a portion of an inner ring according to an exemplary embodiment of the present invention;

figure 4

a portion of a rear part of an exemplary inner ring according to the invention;

Figures 5a, 5b:

each an exploded view of an exemplary inner ring according to the invention with bearing bush and vane.

figure 1 shows a perspective view of a section of a guide vane ring 100. This comprises an inner ring 10 with a radially outer inner ring surface 11 and a plurality of receptacles 12, in each of which a guide vane disk 21a of a guide vane 20 is inserted; For better understanding, a photograph without the guide vane inserted is shown at the edge of the illustration. An intended main flow direction R runs axially from the image background through the inner ring 10 into the image foreground; the adverb "axial" is (just like the adverb “radial”) to be understood in relation to an (abstract) central axis A of the inner ring 10 (and thus of the vane ring 100).

In addition to the guide vane disk 21a positioned radially on the inside, the guide vanes 20 comprise a guide vane disk 21b positioned radially on the outside, which is intended to be fixed to a housing (not shown). A blade 22 is arranged between the guide vane plates 21a and 21b. On the side facing away from the airfoil 22, the guide vane disks 21b positioned radially on the outside have an adjusting pin 23 running radially outward.

Not recognizable in the representation of the figure 1 that the openings of the recordings 12 on the inner ring surface 11 according to the invention radially opposite a bottom surface 14, in the area of which at least two of the recordings 12 are connected to one another by an opening 16. This is shown in the sectional view of the figure 2 clearly.

The figure 2 12 shows a section of an inner ring 10 with an inner ring surface 11 and a plurality of seats 12 for vane plates (not shown). A bearing bush 30 has a radially inner annular surface 31, a radially outer annular surface 32 and a radially extending bore 33 which connects the two annular surfaces 31 and 32 to one another. In the example shown, the bearing bushings 30 for bearing journals (not shown) of the respective vane plates are inserted into the receptacles 12 . The radially inner annular surface 31 of the bearing bush 30 rests on the base surface 14 pointing radially outward.

The bearing pin 24 formed on the radially inner surface 21c of the guide vane plate 21a is later arranged in the bore 33, so that the inner surface 21c rests on the radially outer annular surface 32 of the bearing bush 30; this is in the Figures 5a, 5b shown.

The receptacles 12 each have an opening 13 on the inner ring surface 11 and a bottom surface 14 which is radially opposite to the opening (relative to the inner ring axis); when the vane plate is not used, the bottom surface is visible from the outside when viewed radially. In the example shown, the bottom surfaces 14 each form abutment surfaces for the bearing bushes 30. The bottom surfaces 14 can hold the receptacles 12 Completely or only partially complete radially inwards; in particular, they can in turn have openings (not shown).

A partition wall 15 is arranged between each two adjacent receptacles 12, which separates the receptacles from one another; an extension d of the partition wall in the radial direction (based on the inner ring) is (starting from the inner ring surface) preferably at least 2 mm, more preferably at least 3 mm. In particular, the extension d is preferably at least as great as the thickness (i.e. shell height) of a guide vane plate to be used (measured without the bearing journal), so that it does not protrude from the inner ring surface 11 in the inserted state.

Adjacent receptacles 12 are each connected to one another by an opening 16 in a region of their bottom surface.

These openings 16 enable an advantageous arrangement of the bearing bushes (or those to be used in the receptacles 12, in the figure 2 vane plate not shown) while avoiding an unfavorably thin area of the partition wall: As in the figure 2 As can be seen, the cylindrically shaped receptacles are arranged radially in the inner ring. The distance between each two adjacent recordings thus decreases continuously radially inwards. The distance in the radially outer area (on the inner ring surface 11) is denoted by a ₁ in the figure, the distance in the radially inner area (on the bottom surface 14) by a ₂ ; as can be seen in the figure, a ₁ > a ₂ . Preferably a ₁ is at most 3mm, more preferably at most 2mm. The distance a ₂ is advantageously less than or equal to 0.5 mm, more preferably it is between 0.1 mm and 0.5 mm.

Even with such a narrow arrangement of the receptacles, a correspondingly thin partition wall, which is therefore at risk of deformation, can be avoided according to the invention by arranging the opening 16 in the corresponding area. Its radial height h (starting from an adjacent bottom surface 14) is preferably at least 2mm, more preferably at least 3mm.

The radial height of the opening is preferably less than or equal to a thickness D of the bearing bushes 30 (that is, their radial extension in relation to the inner ring in the inserted state); as a result, leakage at a radially outer surface of the bearing bushes and through the opening can be prevented or at least reduced.

In figure 3 a section of an axially two-part inner ring 10 according to the invention is shown. The inner ring 10 comprises a front inner ring part 10b (in the intended main flow direction) and a rear inner ring part 10a (in the intended main flow direction); this is also in the figure 4 shown in another view. The inner ring parts 10a and 10b are each designed as partial rings, ie in particular also as rings.

The front and rear inner ring parts each have an edge 12b and 12a, which together enclose a plurality of receptacles and each form a section of their boundaries.

In the example shown, the edge 12a of the rear inner ring part 10a has a chamfer 17 in the delimiting section of each receptacle; it enables a pivotable guide vane to be guided correspondingly close to the inner ring.

On the side facing the front inner ring part, the rear inner ring part 10a has a projection 18 which extends in the axial direction and which engages on an outer edge in an annular groove 25 running in the axial direction in the front inner ring part 10b and has a surface which in each case has a Bottom surface 14 forms for the recordings. The bottom surfaces 14 are radially opposite the openings 13 of the receptacles 12 . The bottom surface 14 forms the radially outward-facing surface of the projection 18.

Adjacent receptacles are each separated from one another in the area of the openings of the receptacles (in the inner ring surface) by a partition wall 15 which has a radial height d. In the area of the bottom surfaces 14, adjacent receptacles are each connected to one another by an opening 16. The breakthroughs each have a radial height h, which is preferably in a range of 2mm to 3mm. In the example shown the breakthrough according to the invention has a triangular cross section. As described above, other cross-sectional shapes in the form of a segment of a circle, a round shape or a pointed arch are possible according to the invention.

In particular, the breakthrough can be optimized depending on a shape of the inner ring, for example its size and/or its surface design.

In the embodiment shown, the front and rear inner ring parts can be connected to one another via connecting elements 19 .

From different perspectives, the Figures 5a and 5b each an inner ring 10 according to an embodiment of the present invention with a vane 20 to be used in an exploded view. For an explanation of the individual elements labeled analogously to the above figures, reference is made to their description. As continues in the Figure 5b is marked, the opening 16 has a width b in the axial direction (relative to a central inner ring axis, not shown) in the region of the bottom surface 16 formed by the projection 18; preferably this width b is at least 3mm, more preferably at least 4mm. In this way it is also possible to avoid a partition wall thickness which is too small on the side of a center of the opening (eg in a narrowest region between two receptacles).

An inner ring 10 according to the invention for a guide vane ring of a turbomachine has a radially outer inner ring surface 11 and a plurality of receptacles 12 for a guide vane disk 21a of a guide vane 20 in each case. The receptacles 12 each have an opening 13 in the outer inner ring surface 11 and a bottom surface 14 radially opposite the opening. At least two of the receptacles 12 are separated from one another by a partition 15 and are connected to one another in a region of their bottom surface 14 by an opening 16.

A vane ring 100 according to the invention for a turbomachine has an inner ring 10 according to the invention and a plurality of vanes 20 inserted into the receptacles 12 .

Reference sign

10

inner ring

10a, 10b

inner ring parts

11

inner ring surface

12

Recording

12a, 12b

recording section

13

opening of the recording

14

floor space

15

partition wall

16

breakthrough

17

chamfer

18

head Start

19

fastener

20

vane

21a, 21b

vane plate

21c

radially inner surface

22

shovel blade

23

adjustment pivot

24

bearing journal

25

Groove in inner ring part

30

bearing bush

31

radially inner annular surface

32

radially outer annular surface

33

drilling

100

vane ring

A

central axis

D

Bushing thickness

R

intended main flow direction

a1

Distance between two adjacent sockets

a2

Distance between two adjacent mounts on the inner ring surface

b

Width of breakthrough (in axial direction)

i.e

radial extension of the partition

H

radial height of breakthrough

Claims (10)

1. Inner ring (10) for a guide vane ring (100) of a turbomachine, wherein the inner ring has a radially outer inner ring surface (11) and a plurality of receptacles (12) in each case for a guide vane plate (21a) of a guide vane (20),

   wherein the receptacles each have an opening (13) in the outer inner ring surface and a bottom surface (14) which is radially opposite the opening, wherein at least two of the receptacles (12) are separated from one another by a partition wall (15) and are interconnected in a region of the bottom surface (14) thereof by a through-hole (16),

   characterized in that

   the through-hole (16) has a substantially triangular, circular-segment-shaped, round-arch or pointed-arch cross section in the circumferential direction of the inner ring (10).
2. Inner ring according to claim 1, wherein the receptacles (12) each comprise a substantially cylindrical bore in the inner ring (10), which extends radially relative to the inner ring.
3. Inner ring according to either of claims 1 or 2, wherein the at least two receptacles (12) are spaced apart along the radially outer inner ring surface (11) at a distance (a₁) of at most 3 mm, more preferably at most 2 mm.
4. Inner ring according to any preceding claims, wherein the partition wall (15) between the at least two receptacles (12) extends from the radially outer inner ring surface (11) radially up to 2 mm, more preferably up to 3 mm, into the inner ring (10)
   and/or wherein the through-hole (16) between the at least two receptacles has a radial height (h) of at least 2 mm, more preferably at least 3 mm, starting from the bottom surface (14) of one of the receptacles.
5. Inner ring according to any of the preceding claims, comprising two inner ring parts (10a, 10b) assembled in the axial direction of the inner ring (10), each of which has, in the axial direction of the inner ring (10), an edge which in each case partially delimits the plurality of receptacles.
6. Inner ring according to claim 5, wherein, of the two inner ring parts, a first inner ring part (10a) has, on a side facing a second inner ring part (10b), a projection (18) extending in the axial direction having a surface which forms the bottom surface (14) for the receptacles, the projection engaging on an outer edge in an annular groove (25) of the second inner ring part (10b) extending in the axial direction.
7. Inner ring sector for an inner ring (10) according to any of claims 1 to 6, characterized in that the inner ring sector comprises at least two of the receptacles (12) separated from one another by a partition wall (15) and interconnected in a region of the bottom surface (14) thereof by a through-hole (16), and in that the through-hole (16) has a substantially triangular, circular-segment-shaped, round-arch or pointed-arch cross section in the circumferential direction.
8. Guide vane ring (100) for a turbomachine, comprising an inner ring (10) according to any of claims 1 to 6 and a plurality of guide vanes (20) inserted into the receptacles (12).
9. Guide vane ring according to claim 8, wherein at least two of the inserted guide vanes (20) or bearing bushes (30) inserted into the receptacles for the guide vanes (20) are spaced apart in the region of the through-hole (16) at a distance (a₂) of at most 0.5 mm.
10. Turbomachine comprising a guide vane ring (100) according to either of claims 8 or 9.

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