U.S. patent application number 16/083981 was filed with the patent office on 2020-09-17 for rotor disk assembly having a two-part seal.
This patent application is currently assigned to Siemens Aktiengesellschaft. The applicant listed for this patent is Siemens Aktiengesellschaft. Invention is credited to Peter Schroder, Dirk Springborn.
Application Number | 20200291798 16/083981 |
Document ID | / |
Family ID | 1000004885007 |
Filed Date | 2020-09-17 |
United States Patent
Application |
20200291798 |
Kind Code |
A1 |
Schroder; Peter ; et
al. |
September 17, 2020 |
ROTOR DISK ASSEMBLY HAVING A TWO-PART SEAL
Abstract
A rotor disk assembly having a two-part seal, wherein the rotor
disk assembly has a rotor disk, on which a plurality of sealing
plates is arranged in front of an end side and wherein a plurality
of separate sealing vanes is arranged radially outside of the
sealing plates in a circumferentially distributed manner.
Inventors: |
Schroder; Peter; (Essen,
DE) ; Springborn; Dirk; (Berlin, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Siemens Aktiengesellschaft |
Munich |
|
DE |
|
|
Assignee: |
Siemens Aktiengesellschaft
Munich
DE
|
Family ID: |
1000004885007 |
Appl. No.: |
16/083981 |
Filed: |
March 22, 2017 |
PCT Filed: |
March 22, 2017 |
PCT NO: |
PCT/EP2017/056776 |
371 Date: |
September 11, 2018 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F01D 5/3015
20130101 |
International
Class: |
F01D 5/30 20060101
F01D005/30 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 8, 2016 |
DE |
102016205921.1 |
Claims
1-15. (canceled)
16. A rotor disk assembly, comprising: a rotor disk which has a
multiplicity of axially extending blade retention grooves
distributed on the outer circumference, and an encompassing plate
retention groove, or a plurality of plate retention grooves
distributed on the circumference, in front of an end face beneath
the blade retention grooves, a multiplicity of sealing plates which
have a flat design and extend transversely to the rotor axis and
together form a basically closed ring and are mounted on the
respective inner circumference in the plate retention groove and
cover the blade retention grooves in certain sections, and a
multiplicity of separate sealing vanes which are arranged in front
of the end face adjacent to the outer circumference of the sealing
plates and cover the blade retention grooves in certain sections,
wherein the rotor disk has a multiplicity of circumferentially
distributed mounting bases, which mounting bases extend axially
from the end face beyond the sealing plate, wherein the sealing
vanes have at least one fastening socket in which is arranged the
mounting base.
17. The rotor disk assembly as claimed in claim 16, wherein the
sealing plates are produced in each case from a flat metal sheet;
and/or wherein all the sealing plates are designed as identical
parts.
18. The rotor disk assembly as claimed in claim 16, wherein the
sealing vanes, in a cross section along the rotor axis, are of a
U-shaped or V-shaped radially outward opening design; and/or all
the sealing vanes are designed as identical parts.
19. The rotor disk assembly as claimed in claim 16, wherein the
distance of the mounting base to the rotor axis on the end face is
greater than on its free end.
20. The rotor disk assembly as claimed in claim 16, wherein the
sealing vane has at least two fastening sockets with a free space
in between, which free space, with rotation of the sealing vane
relative to the rotor disk, enables removal of the sealing vane
from the mounting bases in the axial and/or radial direction.
21. The rotor disk assembly as claimed in claim 16, wherein the
mounting base has a constant or reducing thickness perpendicularly
to the underside of the mounting base, measured from the end face
to the free end, and/or the fastening socket, on the side pointing
away from the rotor axis, has an adequate free space which enables
removal in a direction pointing axially and toward the rotor
axis.
22. The rotor disk assembly as claimed in claim 21, wherein at
least one sealing vane has lateral edges extending parallel and
opposite each other in the circumferential direction.
23. The rotor disk assembly as claimed in claim 16, wherein the
sealing vanes, on the side pointing toward the rotor axis, have a
support surface against which butts the sealing plates by an outer
circumferential surface.
24. The rotor disk assembly as claimed in claim 23, wherein the
sealing vanes have a retaining projection, adjacent to the support
surface and pointing toward the rotor axis, against which retaining
projection butts the sealing plates on the outer circumference
opposite the end face.
25. The rotor disk assembly as claimed in claim 23, wherein the
sealing plates, with rotation of the rotor disk assembly, are
supported against the sealing vanes and by means of their
centrifugal force induce torque in the sealing vanes around the
free end of the mounting base.
26. The rotor disk assembly as claimed in claim 16, further
comprising: a locking element which fits through the sealing vane
and/or the sealing plate and engages in a recess on the rotor disk
or rotor blade or acts against an abutment.
27. The rotor disk assembly as claimed in claim 16, further
comprising: a locking element fixedly arranged on the rotor blade,
raised from the end face, and engages in a recess on the sealing
plate and/or on the sealing vane or acts against an abutment.
28. A rotor comprising: a rotor disk assembly as claimed in claim
16.
29. A gas turbine comprising: a rotor as claimed in claim 28.
30. The rotor disk assembly as claimed in claim 16, wherein the
multiplicity of circumferentially distributed mounting bases are
arranged between the blade retention grooves in each case.
31. The rotor disk assembly as claimed in claim 26, wherein the
locking element fits through two adjacent sealing vanes and/or two
adjacent sealing plates and/or sealing vane and sealing plate, at
least in certain sections, and engages in a recess on the rotor
disk or rotor blade or acts against an abutment.
Description
CROSS REFERENCE TO RELATED APPLICATIONS
[0001] This application is the US National Stage of International
Application No. PCT/EP2017/056776 filed Mar. 22, 2017, and claims
the benefit thereof. The International Application claims the
benefit of German Application No. DE 102016205921.1 filed Apr. 8,
2016. All of the applications are incorporated by reference herein
in their entirety.
FIELD OF INVENTION
[0002] The invention relates to a rotor disk assembly having a
rotor disk and sealing elements which are arranged in front of an
end face.
BACKGROUND OF INVENTION
[0003] In a rotor of a gas turbine, use is made as a rule of rotor
disks which have a multiplicity of blade retention grooves,
distributed on the outer circumference, into which a rotor blade is
fastened in each case by means of a blade retention profile. This
enables the exchange of rotor the rotor blade in the case of wear.
It is furthermore known that the blade retention grooves are to be
protected against penetration of the hot gas which flows through
the gas turbine. To this end, circumferentially distributed
segmented sealing plates are inserted in a known manner in front of
the end face of the rotor disk. To this end, known embodiments are
known for example from EP 1 804 338 A1, EP 1 944 471 A1 and from EP
2 399 004 A1. The sealing plates usually have a flat design in
these cases and extend from an annular groove beneath the blade
retention grooves beyond the outer circumference of the rotor disk.
Therefore, the blade retention grooves are reliably covered by the
sealing plates. The fastening of the sealing plates is carried out
on the rotor disk or on the rotor blades in different ways, wherein
to this end the sealing plates are usually mounted on the inner
circumference in an annular groove of the rotor disk. The axial
securing of the sealing plates on the outer circumference is
usually similarly carried out in an annular groove which is formed
by the circumferentially segmented adjacent rotor blades.
[0004] Although a suitable covering of the blade retention grooves
on the rotor disk is possible using the available embodiments of
sealing plates, narrow limits are set, due to the high thermal
loads, upon the possibility of enhancing the sealing plates by
further functions without giving rise to an appreciable cost
increase. In particular, the requirement for a further sealing leg,
extending radially in front of the end face, leads to the necessity
of using an expensive material for the sealing plates.
SUMMARY OF INVENTION
[0005] It is therefore the object of the presented invention to
enable the attachment of an additional sealing leg without the
costs increasing to a considerable degree.
[0006] The set object is achieved by means of an embodiment
according to the invention of a rotor disk assembly. A rotor
according to the invention is specified and a gas turbine according
to the invention is specified. Advantageous embodiments are the
subject matter of the dependent claims.
[0007] The generic rotor disk assembly comprises in the first
instance a rotor disk. This has a multiplicity of axially extending
blade retention grooves which are distributed on the outer
circumference. In this case, it is not absolutely necessary that
the blade retention grooves extend parallel to the rotor axis,
although this constitutes the advantageous and inexpensive
embodiment. Rather, it is sufficient if the blade retention grooves
extend from one end face of the rotor disk to the other end face of
the rotor disk. In this case, these can have both a curved
characteristic and advantageously a rectilinear characteristic.
Furthermore, the rotor disk, at least on a side in front of the end
face beneath the blade retention grooves, has an encompassing plate
retention groove or a plurality of circumferentially distributed
plate retention grooves.
[0008] The rotor disk assembly also comprises a multiplicity of
sealing plates which in a circumferentially distributed manner form
a basically closed ring. In essence, reference is made in this
respect to the fact that a slight gap, which is advantageously
arranged in the region between two blade retention grooves, can
remain between the individual sealing plates. The sealing plates
have in this case a flat design and extend transversely to the
rotor axis. In this case, it is not absolutely necessary that the
sealing plates have a constant material thickness over their
extent. It is at least provided that the material thickness in the
axial direction is significantly smaller than its dimensions in the
radial and tangential directions. The sealing plates are mounted in
the rotor disk assembly by their respective inner circumference in
the plate retention groove. Therefore, their movement is limited at
least in the axial direction. In accordance with their task, the
sealing plates in this case cover the blade retention grooves in
certain sections.
[0009] According to the invention, it is now provided that a
multiplicity of sealing vanes are used. These sealing vanes, as
additional sealing elements, supplement the sealing plates for
covering the blade retention grooves. Correspondingly, the
multiplicity of separate sealing vanes also form an encompassing,
basically closed ring, wherein the sealing vanes are also arranged
in front of the end face of the rotor disk. In order to achieve a
covering of the blade retention grooves which is as complete as
possible, the sealing vanes are furthermore arranged directly
adjacent to the sealing plates, wherein the sealing plates are
located adjacent to the sealing vanes on the side pointing toward
the rotor axis.
[0010] By dividing the conventionally used sealing elements for
covering the blade retention grooves into inner sealing plates and
sealing vanes located above them, a greater degree of freedom with
regard to material choice and design is achieved. The sealing
plates can now be produced from an inexpensive material, while on
the other hand there is the possibility in the case of the sealing
vanes of adding further functions in a specific manner.
[0011] In this case, it is particularly advantageous if the sealing
plates are produced in each case from a metal sheet. In this way, a
particularly inexpensive production method is achieved by for
example the sealing plates being stamped out or lasered out of a
metal sheet.
[0012] In contrast, it is advantageous if the sealing vanes, in a
cross section along the rotor axis, are of an O-shaped or V-shaped
radially outwardly opening design. Therefore, it is made possible
to form two spaced apart vane legs, which extend radially in each
case, on the sealing vane.
[0013] It is also advantageous with regard to logistics and
installation if all the sealing plates used on the rotor disk
assembly are designed as identical parts.
[0014] Similar to the sealing plates, it is also advantageous if
all the sealing vanes used in the rotor disk assembly are designed
as identical parts.
[0015] With regard to the segmented division of the sealing surface
and the sealing vanes, it is possible on the one hand to arrange
these in a coinciding number and, moreover, one above the other in
each case. It is advantageous, however, if the sealing plates and
the sealing vanes are positioned in a staggered manner in relation
to each other as seen in the rotation direction. Furthermore, it is
advantageous if the number of sealing vanes and sealing plates vary
in relation to each other.
[0016] For the fastening of the sealing vanes, it is advantageous
if a multiplicity of circumferentially distributed mounting bases
are arranged on the rotor disk. These mounting bases extend in this
case in a particularly advantageous manner beyond the end face of
the rotor disk beyond the sealing plate in the axial direction. In
a simple and advantageous manner the mounting bases are arranged in
this case between two blade retention grooves in each case. When
the corresponding mounting base is being installed, the sealing
vane has at least one fastening socket in which the mounting base
is located. Correspondingly, the sealing vane is fastened on the
rotor disk by locating the mounting base in the fastening
socket.
[0017] The designing of the mounting base can in this case be
carried out in many ways. In the both advantageous and simple
embodiment, the respective mounting base is formed as a section of
a rotor body in each case. This simplifies the production of the
rotor disk and the installation of the sealing vanes.
[0018] It is also advantageous if the free end of the mounting base
has a shorter distance to the rotor axis than the mounting base on
the end face of the rotor disk. For secure retention of the sealing
vanes on the mounting bases, it is particularly advantageous in
this case if the mounting base is in proximity to the rotor axis on
the underside, pointing toward the rotor axis, in the extent from
the end face to the free end of the mounting base. With regard to
this, it is unimportant whether the proximity extends continuously
or discontinuously.
[0019] The mounting base in cross section can be designed in many
ways and can have for example a T-shaped design. Of advantage,
however, is a trapezoidal shape, as seen in cross section, which
becomes larger from the end face toward the free end. Therefore,
when the sealing vane is being mounted onto the mounting bases a
secure retention both in the axial direction and in the radial
direction is enabled.
[0020] In this case, it is particularly advantageous if the sealing
vane has at least two fastening sockets with a free space in
between. With regard to this, it is unimportant whether the sealing
vane furthermore has one or two additional free spaces on both
sides of the fastening sockets or whether the number of fastening
sockets and free spaces is further increased. With rotation of the
sealing vane relative to the rotor disk, the free space which lies
between the fastening sockets at least enables mounting or removal
of the sealing vane on the rotor disk. In a corresponding position
of the sealing vane relative to the rotor disk, the installation of
the sealing vane on the rotor disk leads to an insertion of the
mounting base into the free space, wherein the mating of the
mounting base in the fastening socket is subsequently carried out
by the rotation of the sealing vane relative to the rotor disk.
[0021] Alternatively to this, it is possible to mount an individual
fastening vane or a number of the existing fastening vanes or all
the fastening vanes by means of an inclined movement pointing
toward the rotor axis. To this end, it is necessary that the
mounting base has a constant or reducing material thickness from
the end face to its free end. With regard to this, the material
thickness is to be determined perpendicularly to the underside of
the mounting base. In this case, the fastening vane can be removed
directly without rotation by means of a sliding and/or pivoting
movement of the mounting base with a movement inclined toward the
rotor axis. A similar method of installation is enabled if,
regardless of the specific design of the mounting base, the
fastening socket has an adequate free space on the side pointing
away from the rotor axis so that a possible undercut on the
mounting base does not hinder the installation process.
[0022] It is advantageous in this case if the sealing vane, which
is intended for installation without a rotation, has in each case
lateral edges extending parallel to each other on the sides lying
opposite each other in the circumferential direction. Consequently,
the installation or removal movement pointing radially toward the
rotor axis does not lead to a collision of adjacent sealing vanes
at the lateral edges.
[0023] For the advantageous fastening of the sealing plates, it is
also particularly advantageous if the sealing vanes have a support
surface on the side pointing toward the rotor axis. By an outer
circumferential surface the sealing plates butt against this
support surface, at least during rotation of the rotor disk
assembly. Correspondingly, the sealing plates are radially
supported by means of the sealing vanes. Therefore, a particularly
simple installation and supporting of the sealing plates can be
realized.
[0024] The shape of the support surface or of the outer
circumferential surface is initially unimportant in this case
providing the corresponding abutment for supporting the sealing
plates is ensured. In one advantageous embodiment, it is
correspondingly possible to design the support surface as part of a
cylindrical surface so that a radially oriented abutment of the
outer circumferential surface is ensured. It is also possible for
the support surface to be of an inclined or arc-shaped design as
seen in a cross section along the rotation axis, wherein in this
embodiment case the support surface, similar to the underside of
the mounting base, becomes closer to the rotor axis with increasing
distance from the end face.
[0025] Particularly when selecting the support surface in
cylindrical form, it is particularly advantageous if the sealing
vanes have a retaining projection adjacent to the support surface.
In this case, the retaining projection is arranged at a distance
from the end face by the width of the support surface and extends
radially in the direction of the rotor axis. Correspondingly, by
means of the sealing vane together with the rotor disk a fastening
groove, which is open toward the rotor axis, is realized with the
groove bottom as the support surface. By the seating of the sealing
plates on the outer circumference between the end face and the
retaining projection these are also secured in the axial
direction.
[0026] It is also particularly advantageous if with abutment of the
sealing plates by the outer circumferential surface against the
support surface of the sealing vane the mounting base and the
fastening socket are designed in such a way that with rotation of
the rotor disk assembly a centrifugal force of the sealing plates
acts upon the support surface of the sealing vanes and therefore
torque in the sealing vane is made to act around the free end of
the mounting base. As a result of this, it is ensured that the
sealing vane, even with a center of gravity at a distance from the
end face, is not tilted downward from the mounting base toward the
rotor blades on account of the high centrifugal force forces in the
sealing vane.
[0027] For securing the position of the sealing vane or of the
sealing plate on the rotor disk, a locking element is
advantageously used. This fits through the sealing vane and/or the
sealing plate in this case, at least in certain sections, and
engages in a recess or acts against an abutment on the rotor disk
or the rotor blade. In this case, it can be provided that the
locking element fixes only one sealing vane or one sealing plate,
wherein the locking element is advantageously arranged at the joint
between sealing vane and sealing plate so that by means of the
locking element at least the rotation direction of both elements is
secured at the same time.
[0028] Furthermore, in an alternative embodiment it is possible to
arrange the locking element in a fixed manner on the rotor blade,
wherein this extends axially in a raised manner from the end face.
In this case, by mating the corresponding rotor blade with the
locking element an engagement of the locking element in a recess on
the sealing vane or on the sealing plate or at least against an
abutment on the sealing vane or sealing plate is enabled and
therefore prevents its rotation relative to the rotor disk.
[0029] By realizing a rotor disk assembly with the novel inventive
embodiment using sealing plates and sealing vanes, a new rotor
according to the invention is created for use in a gas turbine.
[0030] Correspondingly, the use of a rotor according to the
invention enables the realization of a gas turbine according to the
invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0031] In the following figures, an exemplary embodiment for a
rotor disk assembly is outlined. In the drawing:
[0032] FIGS. 1 and 2 show a detail of a rotor disk assembly
according to the invention with a rotor disk, sealing plates
arranged on the end face and circumferentially distributed sealing
vanes arranged above them;
[0033] FIG. 3 shows a further perspective view of the rotor disk
assembly;
[0034] FIG. 4 shows the rotor disk assembly similar to FIG. 3 in
section;
[0035] FIGS. 5 to 7 show a sealing vane of the rotor disk assembly
and
[0036] FIG. 8 shows a sealing plate of the rotor disk assembly.
DETAILED DESCRIPTION OF INVENTION
[0037] In the following figures, an exemplary embodiment for a
rotor disk assembly according to the invention is outlined. For
improved perceptibility, only a detail of the rotor disk assembly
is shown here, wherein the complete rotor disk assembly by itself
is obviously clear to the person skilled in the art.
[0038] In FIGS. 1 to 3 and also in the section in FIG. 4, the rotor
disk 01 is first of all to be seen. This has a multiplicity of
blade retention grooves 09 arranged in a circumferentially
distributed manner, which blade retention grooves 09 in this
exemplary embodiment are arranged rectilinearly and parallel to the
rotor axis. The blade retention grooves serve for the receiving of
rotor blades which are to be attached on the rotor disk 01. The
rotor disk assembly also comprises a multiplicity of sealing plates
11 arranged in a circumferentially distributed manner, which
sealing plates 11 are mounted on the rotor disk 01 by their inner
circumference 14 in a plate retention groove 04. The sealing plate
11 as a separate component is shown for this purpose in FIG. 8 and
has a region on the inner circumference 14 pointing radially toward
the rotor axis and a radially outer region on the outer
circumference 15 and also an outer circumferential surface 12. It
is also to be seen that in this exemplary embodiment the sealing
plate 11 has a recess 16 on both sides for securing the sealing
plate 11 in the circumferential direction. The mounting of the
sealing plate 11 on the rotor disk is advantageously to be seen in
FIG. 4, wherein the sealing plate 11 is mounted by the inner
circumference 14 in the plate retention groove which is formed
radially outward from the rotor disk. In this case, the sealing
plate 11 is fixed both in the axial direction. The sealing plate 11
also butts radially against the bottom of the plate retention
groove 04. As intended, the sealing plate 11 covers the blade
retention groove 09 in certain sections on an end face 02 of the
rotor disk 01. As a result of this, the effect of hot gas which
flows in the hot gas path of the gas turbine being able to
penetrate into the lower region of the blade retention grooves 09
is largely avoided.
[0039] Above the sealing plates 11, a multiplicity of sealing vanes
21 are arranged on the rotor disk 01 in a circumferentially
distributed manner. These sealing vanes 21 in this case are also
located in front of the end face 02 of the rotor disk 01 radially
outside the sealing plates 11. In this case, the sealing vanes 21
cover the blade retention grooves 09 on the end face in addition to
the sealing plates 11. In this way, the extensive covering of the
blade retention grooves 09 is achieved by means of the sealing
vanes in addition to the sealing plates 11. For the fastening of
the sealing vanes 21 on the rotor disk 01 it is provided that a
multiplicity of mounting bases 03, upon which the sealing vanes 21
are mounted, are arranged on the rotor disk 01 in a
circumferentially distributed manner. To this end, the sealing
vanes 21 have in each case corresponding fastening sockets 23 on
the side pointing toward the rotor disk 01.
[0040] As is to be seen in the views of 1 to 4, in this exemplary
embodiment the mounting bases 03--which are arranged in each case
between two blade retention grooves 09--are of trapezoidal design
and widen out with increasing distance from the end face 02 to a
free end 05 of the mounting base 03. How the mounting of the
sealing vanes 21 on the rotor disk 01 is carried out, is
advantageously revealed with reference to a sealing vane 21 shown
separately in FIGS. 5 to 7. This sealing vane 21 has three
fastening sockets 23 in the exemplary embodiment on the rear side
pointing toward the end face 02, which fastening sockets 23 are
designed complementary to the mounting bases 03. Located
alternately with the fastening sockets 23 in each case, between
these, are free spaces 24 which are dimensioned in such a way that
an axial mounting of the sealing vane 21 by the free space 24 on
the mounting bases 03 is possible. By rotation of the sealing vane
21 relative to the rotor disk 01 the mating of the mounting base 03
in correspondingly associated sockets 23 on the sealing vane is
carried out.
[0041] Also to be seen in the depicted figures is the shape of the
sealing vane 21 with a U-shaped, radially outward opening design.
Formed as a result of this is a first vane leg 28 which points
toward the end face 02 and extends radially outward, and at a
distance therefrom a second radially extending vane leg 29. For
securing the sealing vane 21 in the circumferential direction, this
has a recess 26 similar to the sealing plate 11.
[0042] The dividing of conventional sealing elements into a
radially inner sealing plate 11 and a radially outer sealing vane
21 is consequently particularly advantageously enabled by a support
surface 22 being arranged on the sealing vane 21 on the side
pointing radially toward the rotor axis, against which support
surface 22 butts the sealing plate 11 by its outer circumferential
surface 12. In this way, the sealing plate 11 is radially fixed by
means of the sealing vane 21. Adjacent to the support surface 22,
the sealing vane 21 also has a retaining projection 25 which
extends radially to the rotor axis and is arranged at a distance
from the rotor disk 01. As a result of this, it is made possible
for the sealing plate 11 to be axially fixed on the outer
circumference 15 between the end face 02 of the rotor disk 01 and
the retaining projection 25 of the sealing vane 21.
[0043] Also to be seen, especially in section in FIG. 4, is that
the mounting base 03 extends beyond the sealing plates 11, i.e. the
free end 05 of the mounting base is further away from the end face
in the axial direction than the sealing plates 11. This, with a
rotation of the rotor disk assembly with a centrifugal force in the
sealing plates 11, has the effect of the sealing plates 11 butting
against the support surface 22 by the outer circumferential surface
12 and of a torque in the sealing vanes 21 around the free end of
the mounting base 03 counteracting an existing torque from the
sealing vanes 21 on account of their own centrifugal force.
Therefore, a tensile load in the mounting base 03 as a result of
the sealing vanes 21 is reduced in the axial direction.
[0044] Also to be seen, especially in FIG. 1, is that the sealing
vanes 21 are arranged in each case in a staggered manner in
relation to the sealing plates 11 by half a length. As a result of
this, on the one hand the effect of the gaps which exist between
two sealing plates 11 in each case aligning with the gaps which
exist between two sealing vanes 21 in each case is avoided.
Furthermore, the staggered arrangement of sealing vane 21 and
sealing plate 11 enables the positioning of a locking element 07,
especially to be seen in FIG. 4, inside the sealing vane 21 at the
same time in the corner between two sealing elements 11. In this
case, the locking element penetrates the sealing vane 21 in the
region of the recess 26 and butts against the recesses 16 of the
adjacent sealing plates 11.
* * * * *