U.S. patent application number 14/415590 was filed with the patent office on 2015-06-25 for blade ring for a turbomachine.
This patent application is currently assigned to SIEMENS AKTIENGESELLSCHAFT. The applicant listed for this patent is Seimens Aktiengesellschaft. Invention is credited to Dimitri Zelmer.
Application Number | 20150176417 14/415590 |
Document ID | / |
Family ID | 48916028 |
Filed Date | 2015-06-25 |
United States Patent
Application |
20150176417 |
Kind Code |
A1 |
Zelmer; Dimitri |
June 25, 2015 |
BLADE RING FOR A TURBOMACHINE
Abstract
A blade ring for an axial turbomachine is provided, having a
blade carrier with a number of retaining grooves and corresponding
blades, the blade roots of which are inserted into the retaining
grooves, wherein the blades, on the underside facing toward a
groove base of the retaining groove, have a recess, the base of
which is at least partially obliquely inclined relative to the
groove base and in which recess is arranged one wedge-shaped
clamping element for pressing the blade root against the support
flanks. A spring element is provided in each recess, the spring
force of which acts on the respective wedge-shaped clamping element
along the retaining groove. Means are provided with which the
wedge-shaped clamping element can be displaced temporarily into a
position in which the blade root is seated in the retaining groove
with play.
Inventors: |
Zelmer; Dimitri; (Essen,
DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Seimens Aktiengesellschaft |
Munich |
|
DE |
|
|
Assignee: |
SIEMENS AKTIENGESELLSCHAFT
Munich
DE
|
Family ID: |
48916028 |
Appl. No.: |
14/415590 |
Filed: |
July 29, 2013 |
PCT Filed: |
July 29, 2013 |
PCT NO: |
PCT/EP2013/065885 |
371 Date: |
January 18, 2015 |
Current U.S.
Class: |
416/221 |
Current CPC
Class: |
F01D 5/323 20130101;
F01D 5/32 20130101; F01D 5/3007 20130101; F04D 29/322 20130101;
F01D 5/14 20130101 |
International
Class: |
F01D 5/32 20060101
F01D005/32; F01D 5/14 20060101 F01D005/14 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 27, 2012 |
DE |
10 2012 213 227.9 |
Claims
1. A blade ring for an axial turbomachine, comprising a blade
carrier having a number of retaining grooves having support flanks
for blades and a corresponding number of blades, the blade roots of
which, which are configured in a manner corresponding to the
retaining grooves, are inserted into the retaining grooves, wherein
at least one of the blades has on the blade root underside thereof
facing toward a groove base of the retaining groove, a recess, the
base of which is at least partially obliquely inclined with respect
to the groove base of the retaining groove and in which there is
arranged in each case a wedge-shaped clamping element for pressing
the blade root against the support flanks, a spring element
provided in each recess, the spring force of which acts along the
retaining groove on the respective wedge-shaped clamping element,
wherein the recess is delimited by a first side wall and a second
side wall located opposite the first side wall, wherein the spring
element is supported on the one hand on the first side wall and on
the other hand on an obtuse end of the wedge-shaped clamping
element, and means for mounting the blade in the retaining groove
without prestress, adapted such that the wedge-shaped clamping
element can be displaced temporarily into a position in which the
blade root sits in the retaining groove without prestress.
2. The blade ring as claimed in claim 1, wherein the spring element
is in the form of a disk spring assembly and an opening is provided
in the first side wall, through both of which a cylindrical pin
arranged at the obtuse end of the wedge-shaped clamping element
extends.
3. The blade ring as claimed in claim 1, wherein the means for
mounting the blade comprises a threaded hole, which is arranged in
the second side wall and into which a mounting screw can be screwed
from the outside to displace the wedge-shaped clamping element
toward the first side wall.
4. The blade ring as claimed in claim 1, further comprising a
plate-like securing element arranged between a blade root underside
and a groove base of the retaining groove facing toward the blade
root underside that secures each of the blades against displacement
along the retaining groove, wherein the ends thereof bear laterally
against the blade carrier.
5. The blade ring as claimed in claim 1, wherein the wedge-shaped
clamping element has an at least partially hollow form.
6. A compressor for a stationary gas turbine comprising: at least
one blade ring as claimed in claim 1.
7. The blade ring as claimed in claim 1, wherein all of the blades
have a recess on the blade root underside thereof facing toward the
groove base of the retaining groove.
Description
[0001] The invention relates to a blade ring for an axial
turbomachine, comprising a blade carrier having a number of
retaining grooves--having support flanks--for blades and a
corresponding number of blades, the blade roots of which, which are
configured in a manner corresponding to the retaining grooves, are
inserted into the retaining grooves, wherein the blades have, on
the blade root underside thereof facing toward a groove base of the
retaining groove, a recess, the base of which is at least partially
obliquely inclined with respect to the groove base of the retaining
groove and in which there is arranged in each case a wedge-shaped
clamping element for pressing the blade root against the support
flanks.
[0002] A subject matter of the generic type is known, for example,
from EP 1 892 380 A1. In accordance with the fastening of
compressor rotor blades to a rotor as is proposed therein, two
wedges are provided for each rotor blade between a blade root
underside and the groove base of the retaining groove. The
inclinations of the two wedges are in this case opposite. A
clamping screw is screwed into the end of each wedge, making it
possible on the one hand to achieve a radial prestressed
positioning of the blade roots on corresponding support flanks of
the retaining grooves. On the other hand, the screwed connection
also serves to fix the rotor blades along the retaining grooves.
Resilient fastening of the rotor blades is achieved by virtue of
the fact that disk springs can be provided beneath the wedges.
[0003] It is perceived to be a disadvantage, however, that a
screwed connection is used. On account of the comparatively harsh
operating conditions and the operating temperatures which arise,
screwed connections of this type may corrode, and therefore
unproblematic disassembly cannot be ensured.
[0004] Furthermore, it is known from EP 1 703 078 A1, for example,
to secure the rotor blades sitting in axial retaining grooves
against displacement along the retaining grooves by using a
securing plate. Here, a securing plate is positioned between the
blade root and the retaining groove on the groove base. Through a
bead on the securing plate, the latter engages into an opening
provided on the root. After the blade has been inserted with the
securing plate and the surrounding ends have been bent at the inlet
and outlet sides of the root, form-fitting securing is achieved. In
order to make it possible to ensure a sufficiently prestressed fit
of the blade in the groove during operation, it is also necessary
for the blade to be mounted with a prestress. Mounting with
prestress leads to unfavorable wear and fretting at the support
flanks, and this increases the risk of cracking. Primarily in the
leading stages of a compressor exposed to axial throughflow, i.e.
in the case of large blades, where particularly large prestressing
forces are required, the mounting or disassembly proves to be
difficult when servicing the blade.
[0005] It is therefore an object of the invention to provide a
blade ring for a turbomachine, in which mounting of blades in the
retaining grooves of a blade carrier without prestress and
therefore with play is made possible, and nevertheless a
sufficiently large prestress is present during operation which
reliably avoids material-damaging wear--for example also through
rattling.
[0006] The object directed to the blade ring for an axial
turbomachine is achieved by the features of claim 1. Advantageous
configurations are indicated in the dependent claims. These can be
combined with one another in any desired way provided this is not
expressly precluded by the dependency references indicated in the
patent claims.
[0007] In the blade ring according to the invention for an axial
turbomachine, comprising a blade carrier having a number of
retaining grooves--having support flanks--for blades and a
corresponding number of blades, the blade roots of which, which are
configured in a manner corresponding to the retaining grooves, are
inserted into the retaining grooves, wherein at least one of the
blades, preferably all of the blades, has or have, on the blade
root underside thereof facing toward a groove base of the retaining
groove, a recess, the base of which is at least partially obliquely
inclined with respect to the groove base of the retaining groove
and in which there is arranged in each case a wedge-shaped clamping
element for pressing the blade root against the support flanks, it
is provided that each recess is provided with a spring element, the
spring force of which acts along the retaining groove on the
respective wedge-shaped clamping element, wherein the recess is
delimited by a first side wall and a second wall located opposite
the first side wall, wherein the spring element is supported on the
one hand on the first side wall and on the other hand on an obtuse
end of the wedge-shaped clamping element, and that provision is
made of means with which, for mounting the blade in the retaining
groove without prestress, the wedge-shaped clamping element can be
displaced temporarily into a position in which the blade root sits
in the retaining groove without prestress.
[0008] In the installed state, the spring element presses the
wedge-shaped clamping element in the direction of its acute end, as
a result of which, in combination with the inclined base of the
recess, a force acts in the radial direction (with respect to the
installed position in an axial turbomachine) on the blade root,
pressing the latter against the support flanks of the retaining
grooves. This effects play-free and at the same time prestressed
fastening of the rotor blade in the retaining groove. The spring
element is therefore supported on the one hand on a first side wall
of the recess and on the other hand on the obtuse end of the
wedge-shaped clamping element. In order to then make it possible
for the blade to be disassembled from or mounted in the retaining
groove without prestress, it is necessary for provision to be made
of means with which the wedge-shaped clamping element can be
displaced temporarily into a position in which the obtuse end of
the wedge-shaped clamping element is closer to the first side wall
than when in the mounted state. In other words: the spring element
is compressed further than is provided for in the mounted state
only for the duration of the disassembly or mounting. Through the
corresponding inclinations of the base of the recess and of the
wedge-shaped clamping element, the displacement of the clamping
element toward the first side wall has a relieving effect for
bracing the rotor blade on the support flanks of the retaining
groove. This gives rise to play along the axis from the groove base
of the retaining groove in the direction of the base of the recess
which is present both for mounting the blade in and for
disassembling the blade from the retaining groove and which in the
meantime makes the desired handling of the blade without prestress
possible. Consequently, it is also the case that no complex
apparatuses are required for pressing the blade into the groove or
pushing the blade out of the groove.
[0009] As a whole, what is thereby obtained is a simpler and
quicker mounting and disassembly process which moreover ensures a
high level of occupational safety for the fitter. At the same time,
the magnitude of the spring force can be achieved by a simple
variation of different spring elements. This is the case
particularly when the spring elements are configured as disk
springs or disk spring assemblies. At the same time, it is possible
for the tolerance of the connection between the blade and blade
carrier to be lowered to an average measure, making it possible to
produce the components in a comparatively inexpensive manner.
[0010] During the operation of the axial turbomachine equipped with
such a blade ring, this prestressing device is constantly adapted
to the radial position of the blade. When formed from rotor blade
rings, the blade will assume its maximum radial position in the
retaining groove during operation under the action of the
centrifugal forces. In parallel therewith, the wedge-shaped
clamping element is pressed in further beneath the blade under the
action of the spring force of the spring element. Therefore, a
particularly high prestress of the blade is retained even when the
rotational speed of the machine decreases. This limits the relative
movements even of comparatively large blades and reduces the wear
in the retaining grooves.
[0011] According to a first advantageous configuration, the spring
element is in the form of a disk spring or disk spring assembly. At
the same time, an opening is provided in the first side wall. At
the same time, a cylindrical pin is arranged at the obtuse end of
the wedge-shaped clamping element and extends both through the disk
spring or the disk spring assembly and into the opening or through
the opening in the side wall. By way of example, the cylindrical
pin can be driven into a bore arranged on the clamping element or
can be firmly adhesively bonded there. In conjunction with the
opening arranged in the side wall, the cylindrical pin has the
function of guiding the spring element and at the same time of
securing the wedge-shaped clamping element, so that the latter
cannot undesirably jump out of the recess during mounting.
[0012] According to a further advantageous development, the means
comprises a threaded hole, which is arranged in the second side
wall and into which a mounting screw can be screwed from the
outside to displace the wedge-shaped clamping element toward the
first side wall. Consequently, firstly the spring element is put
over the cylindrical pin of the wedge-shaped clamping element
before the blade is mounted, and then the cylindrical pin is
introduced into the opening arranged in the first side wall. At the
same time, the wedge-shaped clamping element is placed into the
recess arranged on the underside of the blade root. Then, a
mounting screw having a threaded shank of appropriate length is
temporarily screwed in from the outside through the threaded hole
present in the second side wall, said mounting screw making it
possible for the wedge-shaped clamping element to be displaced in
the direction of the first side wall. The displacement here has to
be effected to such an extent that the wedge-shaped clamping
element is countersunk completely in the recess, and mounting of
the blade with the clamping element with play is thus possible.
Then, the subassembly produced in this way is pushed into the
retaining groove. Once the subassembly and therefore the blade have
assumed the predefined position in the retaining groove, the
mounting screw screwed into the second side wall can be released
again, as a result of which the wedge-shaped clamping element is
pressed in the direction of the second side wall by the spring
element. On account of the inclined face of the wedge-shaped
clamping element and of the base of the recess corresponding
thereto, the wedge-shaped clamping element is pressed into the
narrowing space between the groove base and the base, and comes to
rest against both faces--the groove base and the base. As a result,
the blade root is then braced against the support flanks of the
retaining groove.
[0013] Instead of a threaded connection in the second side wall, it
is also possible for a bayonet connection to be provided, for
example.
[0014] According to a further preferred configuration, a plate-like
securing element arranged between a blade root underside and a
groove base of the retaining groove lying opposite the blade root
underside secures each of the blades against displacement along the
retaining grooves, in that the ends of the plate-like securing
element bear laterally against the blade carrier. When axial
securing of this nature is employed, the plate-like securing
element is located between the groove base and the wedge-shaped
clamping element.
[0015] It is further preferable that the wedge-shaped clamping
element has an at least partially hollow form. This makes the
fastening of the blade more elastic in the direction of prestress
and additionally makes frictional damping possible.
[0016] It is further particularly preferable that the blade ring is
a rotor blade ring, and therefore the blade carrier is in the form
of a rotor disk or shaft and the blade is in the form of a rotor
blade. Nevertheless, the blade ring is also suitable for fastening
guide blades.
[0017] It is particularly preferable to use the blade ring in a
compressor of a stationary gas turbine exposed to axial
throughflow.
[0018] Further advantages and features of the invention will be
explained in more detail on the basis of further exemplary
embodiments. In this respect, further features and advantages will
be indicated in the description of the figures. In the drawing:
[0019] FIG. 1 shows a stationary gas turbine in a longitudinal
partial section,
[0020] FIG. 2 shows the longitudinal section through a blade ring
in the region of a retaining groove with a blade inserted therein
according to a first exemplary embodiment,
[0021] FIG. 3 shows the side view of the section shown in FIG.
2,
[0022] FIG. 4 shows a further side view of a retaining groove with
a blade inserted therein, and
[0023] FIG. 5 shows a longitudinal section analogous to FIG. 2 for
a second exemplary embodiment of a blade ring.
[0024] In all the figures, identical features are provided with the
same reference signs. Even though the invention is described in
detail hereinbelow with reference to a rotor blade ring of a gas
turbine compressor, the invention can also be used in other
turbomachines.
[0025] FIG. 1 shows a stationary gas turbine 10 in a longitudinal
partial section. The gas turbine 10 has, in the interior, a rotor
14, which is mounted rotatably about an axis of rotation 12 and
which is also referred to as a turbine rotor. An intake housing 16,
a compressor 18, a toroidal annular combustion chamber 20 with a
plurality of burners 22 arranged rotationally symmetrically to one
another, a turbine unit 24 and a turbine outlet housing 26 follow
one another along the rotor 14.
[0026] The compressor 18 comprises an annular compressor duct with
compressor stages following one another in cascade in the latter
and composed of rotor blade and guide blade rings 44. The rotor
blades 17 arranged on the rotor 14 are supported by rotor disks and
lie with their freely ending airfoil tips 29 opposite an outer duct
wall 42 of the compressor duct. The compressor duct issues via a
compressor outlet diffuser 36 in a plenum 38. Provided in the
latter is the annular combustion chamber 20 with its combustion
space 28, which communicates with an annular hot gas duct 30 of the
turbine unit 24. Four turbine stages 32 connected in series are
arranged in the turbine unit 24. A generator or a working machine
(not illustrated in either case) is coupled to the rotor 14.
[0027] When the gas turbine 10 is in operation, the compressor 18
sucks in through the intake housing 16 ambient air 34 as the medium
to be compressed and compresses this ambient air. The compressed
air is routed through the compressor outlet diffuser 36 into the
plenum 38, from where it flows into the burners 22. Fuel also
passes via the burners 22 into the combustion space 28. The fuel is
burnt there, with the addition of the compressed air, to form a hot
gas M. The hot gas M subsequently flows into the hot gas duct 30,
where it expands, so as to perform work, at the turbine blades of
the turbine unit 24. The energy released in the meantime is
absorbed by the rotor 14 and is utilized, on the one hand, for
driving the compressor 18 and, on the other hand, for driving a
working machine or electric generator.
[0028] FIG. 2 shows a section through a rotor disk 19 of the rotor
14 of the gas turbine 10 in the region of a retaining groove 21
extending in the axial direction. The rotor disk 19 therefore
represents a blade carrier 46, in the case of which the retaining
grooves 21 are distributed uniformly along the circumference
thereof and in this respect extend in the axial direction of the
gas turbine. The retaining grooves 21 have a dovetail-like cross
section (FIG. 3, FIG. 4) and therefore each comprise two support
flanks 23, against which correspondingly configured bearing
surfaces 25 of a blade root 31 of the blades 27 bear. The blades 27
are in the form of rotor blades.
[0029] A recess 37 is provided on an underside 33 of the blade root
31 which faces toward a groove base 35 of the retaining groove 21.
The recess 37 is delimited by a first side wall 39 and a second
side wall 41 lying opposite the first side wall 39. In the
direction of flow of a medium flowing through the compressor 18,
the first side wall 39 is arranged on the inflow side and the
second side wall 41 is arranged on the outflow side.
[0030] A plate-like securing element 43 with longitudinally slotted
ends is placed in the retaining groove 21 between the underside 33
and the groove base 35. In the pairs of tabs which thereby arise at
both ends, it is the case that at each end both a tab 45 is bent
outward and a tab 45 is bent inward (FIGS. 3 and 4), blocking
displacement of the blade 27 inserted in the retaining groove
21.
[0031] A wedge-shaped clamping element 47 having an acute end 49
and an obtuse end 51 is provided in the recess 37. Arranged at the
obtuse end 51 is a cylindrical pin 53, onto which a total of four
disk springs are threaded as a spring element 55 in the exemplary
embodiment shown. The cylindrical pin 53 extends into an opening 57
arranged in the first side wall 39. The base 59 of the recess 37 is
inclined with respect to the groove base 35 of the retaining groove
21, corresponding to the inclination of the upper face 61 of the
wedge-shaped clamping element 47 as shown in FIG. 2.
[0032] Furthermore, a threaded hole 63 is provided in the second
side wall 41 and--like the opening 57--extends parallel to the
retaining groove 21. A mounting screw 65 required for mounting the
blade 27 can be screwed into the threaded hole 63 and can be used
to displace the wedge-shaped clamping element 47 to the left in
FIG. 2 to such an extent that the obtuse end 51 thereof is
positioned comparatively close to the first side wall 39. The
wedge-shaped clamping element 47 can thereby be countersunk
completely in the recess 37.
[0033] The blade 27 is then mounted in the retaining groove 21 as
follows: firstly, the prefabricated plate-like securing element 43
is inserted into the retaining groove. The plate-like securing
element 43 extends over the entire length of the retaining groove
21, with two of the tabs 45 already being bent on the inflow side
or outflow side transversely to the longitudinal extent thereof.
The outwardly bent tab 45 serves as a stop when the blade 27 is
being pushed into the retaining groove 21. At the other end of the
plate-like securing element 43, for the time being only one of the
two tabs 45 is pre-bent in the radial direction toward the machine
axis. Then, the spring element 55 is placed onto the cylindrical
pin 53 of the wedge-shaped clamping element 47, and these are
inserted together into the opening 57 and the recess 37. The
cylindrical pin 53 then engages into the opening 57, which is in
the form of an elongated hole. Once the inclined face 61 of the
wedge-shaped clamping element 47 bears against the inclined base
59, the mounting screw 65 is then screwed into the threaded hole
63, to such a depth that the wedge-shaped clamping element 47 is
pressed toward the opposite side, i.e. in the direction of the
first side wall 39, to be precise until the wedge base 67 is
located within the recess. It is thereby possible to ensure the
insertion of the blade 27 without prestress. Then, the blade 27 is
pushed into the retaining groove 21 with the prestressed
wedge-shaped clamping element 47. After the blade 27 has been
aligned in the retaining groove 21, the mounting screw 65 is
released and removed from the subassembly. As a result, the
wedge-shaped clamping element 47 is relieved of the force of the
mounting screw and, through the action of the axial forces of the
spring element 55, can press the blade 27 in the retaining groove
21 against the support flanks 23 thereof, and thus prestress it.
Finally, the tab 45 of the plate-like securing element 43 which
hitherto has not been bent is bent in the radial direction away
from the machine axis, and this then secures the blade 27 against
escaping from the retaining groove 21. If the blade 27 fastened in
this way has to be removed from the retaining groove 21, the
working steps are to be carried out in a reverse order. After one
of the tabs 45 has been bent away, the mounting screw 65 is to be
screwed into the threaded hole 63. As a result, the prestress is
released and the blade 27 is relieved of load, after which it can
then be easily pushed out of the retaining groove 21.
[0034] According to a second embodiment shown in FIG. 5, the
wedge-shaped clamping element 47 can have an at least partially
hollow form. The hollow space 69 brings about an elastic prestress
and therefore additionally involves frictional damping.
[0035] As a whole, the invention relates to a blade ring 44 for an
axial turbomachine, comprising a blade carrier 46 having a number
of retaining grooves 21 and a corresponding number of blades 27,
the blade roots 31 of which are inserted into the retaining grooves
21, wherein the blades 27 each have, on the underside 33 thereof
facing toward a groove base 35 of the retaining groove 21, a recess
37, the base 59 of which is at least partially obliquely inclined
with respect to the groove base 35 of the retaining groove 21 and
in which there is arranged in each case a wedge-shaped clamping
element 47 for pressing the blade root 31 against the support
flanks 23. To make it possible to mount the blade 27 in the
retaining groove 21 without prestress and to provide a blade ring
44 which can be used in operation without a screwed connection, it
is provided that each recess 37 is provided with a spring element
55, the spring force of which acts along the retaining groove 21 on
the respective wedge-shaped clamping element 47, and that provision
is made of means with which, for mounting the blade 27 in the
retaining groove 21 without prestress, the wedge-shaped clamping
element 47 can be displaced temporarily into a position in which
the blade root 31 sits in the retaining groove 21 without
prestress.
* * * * *