U.S. patent application number 12/253573 was filed with the patent office on 2009-02-12 for gas turbine honeycomb seal.
This patent application is currently assigned to MTU Aero Engines GmbH. Invention is credited to Reinhold Meier.
Application Number | 20090041610 12/253573 |
Document ID | / |
Family ID | 32477862 |
Filed Date | 2009-02-12 |
United States Patent
Application |
20090041610 |
Kind Code |
A1 |
Meier; Reinhold |
February 12, 2009 |
GAS TURBINE HONEYCOMB SEAL
Abstract
A honeycomb seal which is manufactured by powder metallurgical
injection molding is disclosed. The honeycomb seal is composed
preferably of several segments. Each segment is embodied as a
single piece and has a base element as well as honeycomb elements
that are embodied as a single piece with the base element.
Inventors: |
Meier; Reinhold; (Dorfen,
DE) |
Correspondence
Address: |
CROWELL & MORING LLP;INTELLECTUAL PROPERTY GROUP
P.O. BOX 14300
WASHINGTON
DC
20044-4300
US
|
Assignee: |
MTU Aero Engines GmbH
Munich
DE
|
Family ID: |
32477862 |
Appl. No.: |
12/253573 |
Filed: |
October 17, 2008 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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10537504 |
Nov 30, 2005 |
|
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12253573 |
|
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Current U.S.
Class: |
419/26 ;
419/66 |
Current CPC
Class: |
Y02T 50/671 20130101;
F01D 11/127 20130101; Y02T 50/60 20130101; F02C 7/28 20130101; B22F
2998/00 20130101; F16J 15/444 20130101; B22F 2998/00 20130101; B22F
3/225 20130101; B22F 5/009 20130101 |
Class at
Publication: |
419/26 ;
419/66 |
International
Class: |
B22F 3/12 20060101
B22F003/12; B22F 3/02 20060101 B22F003/02 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 20, 2002 |
DE |
102 59 963.7 |
Nov 21, 2003 |
DE |
PCT/DE2003/003856 |
Claims
1. A method for manufacturing a honeycomb seal for sealing a radial
gap between a rotor and a stator of a gas turbine, comprising the
step of manufacturing the honeycomb seal by powder metallurgical
injection molding.
2. The method of claim 1, further comprising the steps of:
subjecting a molded honeycomb seal to a releasing process to
release a binding agent used in the powder metallurgical injection
molding process; and compressing the molded honeycomb seal after
the releasing process via a sintering process.
3. The method of claim 1, further comprising the steps of forming
the honeycomb seal in a plurality of segments wherein each segment
is formed as a single piece that includes a base element and
honeycomb elements and further wherein the base element bears the
honeycomb elements.
4. The method of claim 3, further comprising the steps of
connecting the plurality of segments to a supporting structure and
manufacturing the plurality of segments and the supporting
structure of different materials.
5. The method of claim 4, further comprising the steps of
connecting a guide section of the base element to the supporting
structure and interlocking adjacent segments with each other by
engaging a projection of a first segment with a recess of an
adjacent second segment.
6. A method of forming a honeycomb seal, in particular to seal a
radial gap between a rotor and stator of a gas turbine, comprising
the step of forming a base element of the honeycomb seal with
honeycomb elements of the seal as a single piece.
7. The method of claim 6, further comprising the steps of: forming
the base element in a first material; and forming the honeycomb
elements in a second material.
8. The method of claim 6, further comprising the steps of: forming
the honeycomb seal in a plurality of segments, wherein each segment
includes a base element and honeycomb elements; forming a first
segment of the plurality of segments in a first material; and
forming a second segment of the plurality of segments in a second
material.
9. The method of claim 6, further comprising the steps of: forming
the honeycomb seal in a plurality of segments, wherein each segment
includes a base element and honeycomb elements; forming a first
segment of the plurality of segments in a first physical geometry;
and forming a second segment of the plurality of segments in a
second physical geometry.
Description
[0001] This application is a divisional of U.S. application Ser.
No. 10/537,504, which was the National Stage of International
Application No. PCT/DE2003/003856, filed Nov. 21, 2003, the
disclosures of which are expressly incorporated by reference
herein.
BACKGROUND AND SUMMARY OF THE INVENTION
[0002] The present invention relates to a honeycomb seal, which is
preferably used as a seal between a stationary component and a
moving component, in particular between a rotor and stator of a gas
turbine.
[0003] Gas turbines, which are used as engines in airplanes for
example, as a rule include several stationary guide blades as well
as several rotating moving blades. A stationary housing surrounds
the guide blades and the moving blades. The rotating moving blades
rotate relative to the stationary housing, wherein a radial gap is
formed between the blade tips of the rotating moving blades and the
housing. There is also a comparable gap between the radial inside
ends of the guide blades and the rotor bearing the moving blades.
This radial gap should be kept as small as possible in order to
optimize the efficiency of the gas turbine. Hence it follows from
this that even though the radial gap is required on the one hand to
guarantee the rotatability of the moving blades vis-a-vis the
housing, on the other hand, the radial gap is disadvantageous for
efficiency reasons.
[0004] As a result, honeycomb seals are used in gas turbines. The
honeycomb seals seal the radial gap between the rotating moving
blades and the stationary housing, on the one hand, and, on the
other hand, facilitate the rotatability of the moving blades
vis-a-vis the housing without the blade tips of the moving blades
being damaged during rotation. These honeycomb seals are used in
the same way in the gap between the guide blades and the rotor.
Moving blades can run directly against these types of honeycomb
seals with their blade tips or with the so-called sealing fins on
their blade cover bands.
[0005] Prior art honeycomb seals are made of a basic body and
honeycomb elements, wherein the honeycomb elements and the basic
body are separate components, which are connected to each other via
high-temperature soldering in a vacuum. The honeycomb elements are
ground to size and then deburred. The shape and size of the
honeycomb elements is the same for the most part. The design
freedom of the honeycomb seal is limited.
[0006] Starting from this, the present invention is based on the
objective of creating a novel honeycomb seal in which greater
design freedom is possible, and which is simpler to manufacture in
terms of the manufacturing process.
[0007] According to the invention, the honeycomb seal is
manufactured by powder metallurgical injection molding. Powder
metallurgical injection molding is also designated as metal
injection molding (MIM). The present invention proposes for the
first time that a honeycomb seal be manufactured by powder
metallurgical injection molding. This results in greater design
freedom for the honeycomb seal. In addition, the manufacturing
costs are lower. The grinding and deburring processing steps are
eliminated. In addition, a weight reduction is produced for the
honeycomb seal in accordance with the invention.
[0008] According to another aspect of the present invention, the
honeycomb seal has a base element and honeycomb elements that are
embodied as a single piece with the base element. The honeycomb
seal is preferably composed of several segments with honeycomb
elements, wherein each segment has a base element and honeycomb
elements that are embodied as a single piece with the base element.
As a result of this, it is possible to provide the honeycomb seal
with different properties in sections, e.g., with different
geometries or material properties, in order to thereby adapt the
honeycomb seal in sections or in segments to the desired
properties.
[0009] The honeycomb elements and the base element can be composed
of different materials, wherein the honeycomb elements, e.g.,
should be easy to abrade and the base elements should possess high
temperature resistance.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] Without being limited to these, exemplary embodiments of the
invention are explained on the basis of the drawings. The drawings
show the following:
[0011] FIG. 1 is a schematic, perspective side view of a honeycomb
seal in accordance with the invention as defined by a first
exemplary embodiment of the invention.
[0012] FIG. 2 is a schematic, perspective side view of a honeycomb
seal in accordance with the invention as defined by a second
exemplary embodiment of the invention.
[0013] FIG. 3 is a schematic, perspective side view of a honeycomb
seal in accordance with the invention as defined by a third
exemplary embodiment of the invention.
DETAILED DESCRIPTION OF THE DRAWINGS
[0014] FIGS. 1 through 3 show different embodiments of honeycomb
seals in accordance with the invention. The honeycomb seals shown
there are preferably used to seal a gap between rotating moving
blades and a stationary housing of a gas turbine. Alternatively,
the honeycomb seals are used for sealing between guide blades and
the rotor of a gas turbine. Thus, these types of honeycomb seals
assume the task of sealing a radial gap between blade tips or
sealing fins on cover bands of the rotating moving blades and the
stationary housing in gas turbines that are used as aircraft
engines for example. In order to achieve optimal efficiency of the
gas turbine, the gap between the blade tips or sealing fins on the
cover bands of the moving blades and the housing should be embodied
to be as small as possible. However, so that the blade tips of the
moving blades are not damaged during the rotation of the moving
blades, the honeycomb seal must seal not only the radial gap, but
also protect the blade tips or sealing fins from damage.
[0015] FIG. 1 shows a honeycomb seal 10 in accordance with a first
exemplary embodiment of the invention. The honeycomb seal 10 shown
is slid onto a supporting structure 11. The honeycomb seal 10 has a
base element 12, wherein the base element 12 bears honeycomb
elements 13. The base element 12 and the honeycomb elements 13 are
embodied as a single piece. According to the invention, the
honeycomb seal 10 is manufactured by powder metallurgical injection
molding. Powder metallurgical injection molding is also designated
as metal injection molding. Details about this manufacturing method
are known from the relevant literature.
[0016] At this point it should be noted with respect to powder
metallurgical injection molding that products manufactured with the
aid of this manufacturing process are distinguished by geometric
design freedom. In the case of powder metallurgical injection
molding, a metal powder is mixed with a binding agent to form a
homogenous mass. The volume percent of the metal powder in this
case is preferably greater than 50%. Injection molding is used to
process this homogenous mass of binding agent and metal powder. In
this connection, molded bodies are manufactured. In the case of the
present invention, the molded bodies correspond to the honeycomb
seal in accordance with the invention. These molded bodies already
feature all typical features of the desired honeycomb seal.
However, they have a volume that is increased by the content of the
binding agent. Subsequently, the molded parts are subjected to a
releasing process. Depending upon the binding agent used, it is
either thermally disintegrated, vaporized or extracted via a
solvent. The remaining porous molded bodies are then compressed via
sintering using various inert gases or a vacuum to form the
components with the final geometrical properties. The finished
component is available once this is complete.
[0017] Consequently, it is within the meaning of the present
invention to manufacture the honeycomb seal 10, which is composed
of a base element 12 and of honeycomb elements 13 connected as a
single piece with the base element, using powder metallurgical
injection molding.
[0018] The base element 12 of honeycomb seal 10 in FIG. 1 has
lateral guide sections 14, which can be used to slide the honeycomb
seal 10 on the supporting structure 11. Consequently, the contour
of the guide elements 14 is adapted to the contour of the
supporting structure 11 onto which the honeycomb seal 10 is
supposed to be slid.
[0019] FIG. 2 shows a second honeycomb seal 15 in accordance with
the invention. The honeycomb seal 15 in FIG. 2 also has a base
element 16 and honeycomb elements 17 that are connected as a single
piece with the base element 16. Present again in the area of the
base element 16 is a guide element 18, which can be used to slide
the honeycomb seal 15 into a supporting structure 19. The honeycomb
seal 15 of the exemplary embodiment in FIG. 2 is also manufactured
using powder metallurgical injection molding.
[0020] Already at this point reference should be made to the fact
that the honeycomb seals 10 or 15 of the exemplary embodiments in
FIGS. 1 and 2 are preferably composed of several segments. Thus,
several segments within the meaning of the exemplary embodiments in
FIGS. 1 and 2 can be slid onto the corresponding supporting
structure. All segments then in turn have a base element 12 or 16
and honeycomb elements 13 or 17 that are embodied as a single piece
with the base element. As FIG. 3 shows, the segments have slots for
circumferential sealing purposes and tongues on the opposing end of
the segment. These tongues engage in the slots of the respective
adjacent segments. The slots and the tongues are manufactured as
integral elements during the MIM process.
[0021] FIG. 3 shows another exemplary embodiment of a honeycomb
seal 20 in accordance with the invention. The honeycomb seal 20
shown there also has a base element 21 as well as honeycomb
elements 22 embodied as a single piece with the base element 21.
FIG. 3 shows that the honeycomb elements 22 have different
geometric shapes, whereby different areas are possible, in
particular, in the axial direction.
[0022] The edges of the base element 21 serve as guide elements in
order to slide the honeycomb seal 20 into a supporting structure
23. In the exemplary embodiment depicted in FIG. 3, the edge areas
of the base element 21 accordingly form wedge-shaped guide elements
24, which engage in corresponding recesses in the supporting part
23 or are slid into the supporting part.
[0023] The honeycomb seal 20 in the exemplary embodiment in FIG. 3
is also preferably composed of several segments. As FIG. 3 also
shows, the segment of the honeycomb seal 20 that is depicted in
FIG. 3 has a recess 25 on one end and a projection 26 on an
opposing end. If several segments within the sense of FIG. 3 are
positioned in the supporting structure 23, then the segments
interlock with each other to avoid axial relative displacements. In
this case, then a projection 26 of a segment of the honeycomb seal
20 engages in a corresponding recess 25 of an adjacent segment. The
segments of the honeycomb seal in the exemplary embodiment in FIG.
3 are also manufactured using powder metallurgical injection
molding.
[0024] The honeycomb seals 10, 15 and 20 of the exemplary
embodiments according to FIGS. 1 through 3 possess a great degree
of design freedom. Thus, honeycomb seals whose honeycomb elements
can be individually adapted in terms of their geometrical design
can be manufactured with the aid of powder metallurgical injection
molding. Using powder metallurgical injection molding to
manufacture the honeycomb seal in accordance with the invention
reduces manufacturing expenditures. The grinding and deburring of
the honeycomb seal that are required by the prior art are
eliminated. In addition, the honeycomb seals of the invention are
distinguished by a lower weight. This is particularly advantageous
for aircraft engines. As a whole, the honeycomb seal in accordance
with the invention can be manufactured in a more favorable manner.
Also possible are higher manufacturing penetration and therefore
value added.
[0025] Furthermore, it is possible for the honeycomb seals 10, 15,
20 to be manufactured from another material than the supporting
structures 11, 19 or 23. Thus, the supporting structures can be
manufactured from ceramics for example. In the case of the
supporting structures 11, 19 or 23, these are components that are
used in aircraft engines in the housing of the engines. The
honeycomb seals 10, 15, 20 or segments of the honeycomb seals can
then be inserted in a simple manner into the supporting structures
11, 19 or 23 that are fastened in the housing of the engine.
[0026] The honeycomb seals 10, 15 and 20 can also be manufactured
as a single piece with the supporting structures 11, 19 or 23 using
MIM technology, i.e., using powder metallurgical injection molding,
wherein this integral part can be arranged directly in the
housing.
[0027] Because of the low costs and the simple manufacturing, the
honeycomb seals 10, 15 and 20 can be used as disposable parts.
[0028] The precision of the MIM method to manufacture the honeycomb
seal is so high that even the finest structures can be embodied,
such as the honeycomb elements 13, 17, 22, the tongue that
cooperates with the slot or even part numbers.
* * * * *