EP3056683B1 - Axially split inner ring for a flow machine and guide blade assembly - Google Patents

Description

The present invention relates to an axially divided inner ring for a turbomachine according to the preamble of claim 1. Furthermore, the present invention relates to a vane ring according to claim 10.

In turbomachines, in particular in axial gas turbines, guide wheels (hereinafter the term stator and vane ring are used synonymously) are often connected at the radially inner end with inner rings for stabilizing the guide vanes and for fastening inlet seals. The inlet seals should at least reduce leakage flow between an internal rotor and the vane ring. For the inner rings, there are different embodiments. For example, there are multi-part inner rings that can be divided both radially, axially and in the circumferential direction. Axially split inner ring segments are usually bolted together. Furthermore, radially divided inner ring segments with inlet seals (radially inward) can be pushed or plugged onto the axially screwed inner ring segments (radially outward). The screw connections of the axially divided inner ring segments are potential weak points in terms of material overload, material aging with material breakage, inadequate installation (eg excessive tightening torques in the screw connection), etc. in the operating case of the turbomachine.

In the US 2007/286719 A1 discloses a guide vane assembly of a turbomachine with a cover plate, wherein the cover plate has an inlet seal and is secured to an axially split inner ring.

In the US 5,421,703 A. an arrangement is disclosed on an inner ring at the radially inner end of a guide vane of a turbomachine.

In the article " New dimensions in screw locking. Irrespective of the material and surface condition, the adhesive cures "(Source: Kleben & Dichten Adhesion, 37 (1993) No. 4 Münch en) a screw lock is disclosed by gluing.

An object of the present invention is to propose an axially divided inner ring for turbomachines, on the one hand reduces leakage flows between a rotor and a vane ring of the turbomachine and on the other hand provides a backup in case of damage of fasteners in or on the inner ring.

The object of the invention is achieved by an axially divided inner ring having the features of claim 1. It is further solved by a vane ring with the features of claim 10.

According to the invention, an axially divided inner ring for a turbomachine for fastening to guide vanes of the turbomachine is thus proposed. The inner ring comprises at least a first, solid, upstream annular segment and a second, solid, downstream annular segment. The first ring segment is releasably connected to the second ring segment by means of at least one fastening element.

According to the invention, either the first or the second ring segment is connected to at least one sealing segment. Furthermore, the inner ring comprises a securing element for securing the fastening element, wherein the securing element is connected to the first ring segment and / or with the second ring segment.

The securing element is arranged separately from the fastening element.

Advantageous developments of the present invention are the subject of subclaims and embodiments.

Inventive exemplary embodiments may have one or more of the following features.

In the following, gas turbines will be described purely by way of example purely as turbomachines, but without wishing to restrict turbomachines to gas turbines. The turbomachine may in particular be an axial flow machine. The gas turbine may in particular be an axial gas turbine, for example an aircraft gas turbine.

A solid ring segment according to the invention is in particular a ring segment which has no cavity. A hollow ring segment would be, for example, a ring segment, which has one or more cavities for weight reduction with a structurally high rigidity of the component.

In certain embodiments according to the invention, the first ring segment and the second ring segment are arranged axially one behind the other in relation to the main flow direction of the turbomachine. The two ring segments can interlock in different ways. For example, the second ring segment, the first ring segment, or vice versa, enclose a U-shaped or L-shaped fit together. The ring segments can be wholly or partially positively connected to each other.

In certain embodiments of the invention, the first ring segment and / or the second ring segment is segmented in the circumferential direction. For example, the first ring segment and / or the second ring segment in the circumferential direction have half rings each with a circumferential angle of 180 degrees. The ring segments can also be divided several times, for example, in three segments, each with 120 degrees circumferential angle, in four segments each with 90 degrees circumferential angle, etc. The ring segments can continue to be divided into segments with different circumferential angles.

In some embodiments according to the invention, the fastening element frictionally connects the first ring segment to the second ring segment. For example, the ring segments may have flat, curved or profiled surfaces, which are pressed non-positively by means of a fastener.

In some embodiments of the invention, the fastener is a screw. Several screws can be arranged over the circumference of the first and / or the second ring segment. The screws can be countersunk screws or any other type of screws.

In some embodiments of the invention, the screw, or a plurality of screws, is disposed in a threaded insert for connecting the first ring segment to the second ring segment, or vice versa. By means of the threaded insert, an internal thread for the screw can be made by a hollow cylinder ("insert") is inserted with an internal thread in the first ring segment or in the second ring segment. The threaded insert may be a wire thread insert.

In certain embodiments of the invention, the securing element is positively connected to the first ring segment and / or to the second ring segment. The securing element may be a pin or a security wire, which is introduced into a positive retention on one or both ring segments and connected thereto. The fuse wire can be secured after the positive connection against accidental loosening, for example by bending or bending of parts of the fuse wire.

In certain embodiments of the invention, the securing element is segmented in the circumferential direction. A segmented securing element in the circumferential direction may be a ring segment. The ring segment can be positively and / or non-positively connected to one and / or two axially divided inner ring segments, in particular detachably connected again. The fuse element formed as a segmented ring segment can be designed as a segmented annular disk.

In some embodiments of the invention, the securing element is disposed in radial grooves of the first ring segment or the second ring segment. The securing element is in particular a segmented annular disc. The radial grooves can ensure a guide and / or a safeguard against axial falling out or loosening of the respective ring segment. The radial grooves have, in particular in cross-section U-shaped profiles.

In a fastener configured as a screw, the securing element can be arranged on the front side to the screw head.

One of the fastener separately arranged securing element may be a separate arrangement. A separate arrangement may mean that the securing element has no direct contact with the fastening element. The securing element is not connected positively or non-positively with the fastening element.

In certain embodiments according to the invention, the inner ring has exactly one securing element per fastening element. For example, each fuse wire secure a screw as a fastener. The securing wire can be positively connected by means of one or more brackets with at least one axially divided inner ring segment.

Some or all embodiments according to the invention may have one, several or all of the advantages mentioned above and / or below.

By means of the axially divided inner ring according to the invention can advantageously be used as fasteners in the design and construction of small turbomachines small screws. For example, with small compressor sizes used correspondingly small screw diameter, since in a possible damage, z. B. when tearing off a screw head, no or only a small risk that fractions of screws get into the main flow channel or in another gas channel.

The axially divided inner ring according to the invention allows the inclusion or the encapsulation of screw parts in case of damage, for example in material fatigue of the screw or excessive tightening torques during assembly of the screw. Furthermore, an axially divided inner ring can keep the sealing gap between an inlet seal (stator) and sealing fins (rotor) comparatively constant small, compared to a sealing gap on a radially divided inner ring. A radially divided inner ring usually has design-related clearance fits and larger sealing gaps.

By means of the axially divided inner ring according to the invention can advantageously the number of parts of the inner ring and thus the weight of the inner ring and their cost can be reduced. Furthermore, the space required for the axially divided inner ring according to the invention can be reduced compared to inner rings with radial inner ring segments.

On the axially divided inner ring according to the invention, inlet seals can be fixed without using further, in particular radial, inner ring segments. A costly further, radial seal carrier can advantageously be omitted.

Fig. 1

zeigt eine Schnittdarstellung eines erfindungsgemäßen axial geteilten Innenrings mit einem Ringsegment als Sicherungselement;

Fig. 2

zeigt eine perspektivische Ansicht eines erfindungsgemäßen Innenrings mit einem Ringsegment als Sicherungselement;

Fig. 3

zeigt eine Schnittdarstellung eines erfindungsgemäßen Innenrings mit einem Sicherungsdraht als Sicherungselement;

Fig. 4

zeigt eine perspektivische Ansicht eines erfindungsgemäßen Innenrings mit einem Sicherungsdraht als Sicherungselement; und

Fig. 5

zeigt schematisch stark vereinfacht eine Gasturbine mit einem erfindungsgemäßen Leitschaufelkranz.

The present invention will be explained in the following with reference to the accompanying drawings, in which identical reference numerals designate identical or similar components, by way of example. In each schematically simplified figures:

Fig. 1

shows a sectional view of an axially divided inner ring according to the invention with a ring segment as a securing element;

Fig. 2

shows a perspective view of an inner ring according to the invention with a ring segment as a securing element;

Fig. 3

shows a sectional view of an inner ring according to the invention with a locking wire as a securing element;

Fig. 4

shows a perspective view of an inner ring according to the invention with a locking wire as a securing element; and

Fig. 5

shows schematically greatly simplified a gas turbine with a vane ring according to the invention.

Fig. 1 shows a sectional view of an axially divided inner ring 100 according to the invention. For clarity, a first, solid, upstream arranged inner ring segment 1, a second, solid, downstream arranged inner ring segment 3 and a formed in this embodiment as inner ring segment 5 fuse element hatched.

The first ring segment 1 and the second ring segment 3 are connected or fixed with a screw 7 as a fastener, non-positively. The screw 7 is screwed into a threaded insert 9, which is fixed in the first ring segment 1. Such threaded inserts 9 are often used for highly loaded connections, for example, if the material into which the threaded insert 9 is inserted, does not have sufficient strength for a screw connection. The threaded insert 9 is in particular a wire thread insert.

The screw 7 is exemplified as a countersunk screw. According to the invention, other types of screws can be used with other screw heads.

The inner ring 100 according to the invention is connected at the radially inner end, with respect to the radial direction r perpendicular to the axial direction a (which is also the main flow direction 11 of the turbomachine), with adjustable guide vanes 13. A shoulder 15 of the vane 13 is mounted about an axis of rotation 17 in a recess 19.

At the radially inner end of the inner ring 100, inlet seals 21 (for example, honeycomb seals) are arranged. In the installed state of the turbomachine, a sealing gap is formed by the fact that between the static inlet seals 21 on the inner ring 100 on the one hand and on rotating sealing tips, the so-called sealing fins 23 on a rotor shaft of the turbomachine on the other hand by means of a stripping of the sealing fins 23 at the inlet seals 21 a gap is formed , These Gap seal is intended to minimize the flow losses during operation of the turbomachine between the inlet seals 21 and the sealing fins 23 of the rotor shaft.

The trained as a fuse element ring segment 5 is frontally opposite the screw head 25 is arranged. The ring segment 5 is guided in radial grooves 27. If the screw 7 solves, for example, in an unforeseen way from the threaded insert 9 or the screw breaks 7 in case of damage (for example, by excessive tightening torques during assembly of the screw 7), can be advantageously prevented by means of the ring segment 5 that the screw 7 or parts thereof is moved into the space 29 between the inner ring 100 and the rotor of the turbomachine or even moved into the main flow channel and there may cause high damage (secondary damage), for example, to the rotor blades. This risk is the higher, the smaller the inner rings 100 and thus the screws 7 are dimensioned.

Fig. 2 shows a perspective view of an axially divided inner ring 100 according to the invention with the ring segment 5 as a securing element, with the first inner ring segment 1, the second inner ring segment 3 and the inlet seals 21. The ring segment 5 is guided in radial grooves 27.

The inner ring 100 (division plane T1) divided in the axial direction a is also divided or segmented in the circumferential direction u (division plane t2; drawing plane). A segmented inner ring 100 means in this embodiment that the individual segments of the inner ring 100, ie the first ring segment 1, the second ring segment 3, the ring segment 5 and the inlet seals 21 are segmented. The segments are in the division plane t2 by means of pins (in Fig. 2 not shown) which are inserted or plugged into jacks 31 (or bores), merged and connected.

For example, the inner ring 100 may be divided into two segments each having a 180 ° (degree) circumferential angle, three segments each having a 120 ° (degree) circumferential angle, four segments each having a 90 ° (degree) circumferential angle, or other segmentations.

Fig. 3 shows a sectional view of an axially divided inner ring 100 according to the invention with a fuse wire 33 as a fuse element. The fuse wire 33 is fixed by means of brackets 35 or positively connected to the first inner ring segment 1. Of the Safety wire 33 secures the screw 7 (as a fastener for connecting the first inner ring segment 1 to the second inner ring segment 3) against unintentional loosening or fixing of screw parts in case of breakage of the screw 7, and thus preventing major damage in the turbomachine.

Fig. 4 shows a perspective view of an inner ring 100 according to the invention with a securing wire 33 as a securing element for the screw 7. In the installed state of the fuse wire 33 is first pushed under the brackets 35 and secured the screw 7 against loosening. Subsequently, the fuse wire 33 itself is secured against being loosened or dropped out by bending the tip of the fuse wire 33 (in FIG Fig. 4 indicated by the arrow 37).

The holders 35 can be connected to the first inner ring segment 1, for example by means of soldering, welding, gluing or by another method. Likewise, the holders 35 can be produced by means of a generative method in the production of the inner ring segment 1.

Fig. 5 schematically shows a gas turbine 39, in which a guide vane ring 41 according to the invention can be mounted.

LIST OF REFERENCE NUMBERS

100

inner ring

a

axially; axially

r

radial; radial direction

u

circumferentially

t1

Division plane in the axial direction

t2

Division plane in the circumferential direction

1

first ring segment

3

second ring segment

5

Ring segment

7

screw

9

threaded insert

11

Main direction of flow

13

vane

15

paragraph

17

axis of rotation

19

deepening

21

inlet seal

23

sealing fin

25

screw head

27

Groove (radial)

29

Space between inner ring and rotor of the turbomachine

31

Rifle; drilling

33

fuse wire

35

bracket

37

Bending direction for securing the safety wire

39

gas turbine

41

vane ring

Claims (11)

1. Axially split inner ring (100) for a turbomachine, for fastening to guide vanes (13) of the turbomachine, the inner ring (100) comprising at least a first ring segment (1) arranged upstream and a second ring segment (3) arranged downstream, and the first ring segment (1) being detachably connected to the second ring segment (3) by means of at least one fastening element,
   characterized in that

   - either the first ring segment (1) or the second ring segment (3) is connected to at least one sealing segment, and

   - the inner ring (100) comprises a securing element for securing the fastening element, the securing element being connected to the first ring segment (1) and/or to the second ring segment (3), and the securing element being arranged separately from the fastening element.
2. Inner ring (100) according to claim 1, wherein the fastening element frictionally connects the first ring segment (1) to the second ring segment (3).
3. Inner ring (100) according to either claim 1 or claim 2, wherein the fastening element is a screw (7).
4. Inner ring (100) according to claim 3, wherein the screw (7) is arranged in a threaded insert (9) for connecting the first ring segment (1) to the second ring segment (3), or vice versa.
5. Inner ring (100) according to any of the preceding claims, wherein the securing element is form-fittingly connected to the first ring segment (1) and/or to the second ring segment (3).
6. Inner ring (100) according to any of the preceding claims, wherein the securing element is segmented in the peripheral direction.
7. Inner ring (100) according to any of the preceding claims, wherein the securing element is arranged in radial grooves (27) in the first ring segment (1) or the second ring segment (3).
8. Inner ring (100) according to any of claims 4 to 6, wherein the securing element is arranged in the region of the screw head (25) at the end face thereof.
9. Inner ring (100) according to any of the preceding claims, wherein the inner ring (100) has one securing element per fastening element.
10. Guide vane ring (41) of a turbomachine comprising guide vanes (13), which turbomachine has an inner ring (100) according to any of the preceding claims.
11. Guide vane ring (41) according to claim 10, wherein the guide vane ring (41) is connected to a housing of a compressor, in particular of an axial high-pressure compressor.

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