U.S. patent application number 14/119242 was filed with the patent office on 2014-03-27 for turbocharger and component therefor.
This patent application is currently assigned to BORGWARNER INC.. The applicant listed for this patent is Munevera Kulin, Gerald Schall. Invention is credited to Munevera Kulin, Gerald Schall.
Application Number | 20140086755 14/119242 |
Document ID | / |
Family ID | 47296681 |
Filed Date | 2014-03-27 |
United States Patent
Application |
20140086755 |
Kind Code |
A1 |
Schall; Gerald ; et
al. |
March 27, 2014 |
TURBOCHARGER AND COMPONENT THEREFOR
Abstract
A component for turbocharger applications, in particular in
diesel engines, which has an iron-based alloy having a ferritic
base structure which has a carbide and nitride structure.
Inventors: |
Schall; Gerald;
(Bobenheim-Roxheim, DE) ; Kulin; Munevera;
(Kirchheimbolanden, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Schall; Gerald
Kulin; Munevera |
Bobenheim-Roxheim
Kirchheimbolanden |
|
DE
DE |
|
|
Assignee: |
BORGWARNER INC.
Auburn Hills
MI
|
Family ID: |
47296681 |
Appl. No.: |
14/119242 |
Filed: |
May 24, 2012 |
PCT Filed: |
May 24, 2012 |
PCT NO: |
PCT/US2012/039278 |
371 Date: |
November 21, 2013 |
Current U.S.
Class: |
416/241R |
Current CPC
Class: |
C22C 38/04 20130101;
F01D 5/12 20130101; C22C 38/38 20130101; F01D 25/24 20130101; C22C
38/001 20130101; C22C 38/26 20130101; F05D 2300/13 20130101; C22C
38/22 20130101; C22C 38/28 20130101; C22C 38/02 20130101; F02C 6/12
20130101; C22C 38/24 20130101 |
Class at
Publication: |
416/241.R |
International
Class: |
F01D 5/12 20060101
F01D005/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 7, 2011 |
DE |
102011103535.8 |
Claims
1. A component for turbocharger applications, in particular in
diesel engines, comprising an iron-based alloy having a ferritic
base structure comprising a carbide and nitride structure.
2. The component for turbocharger applications as claimed in claim
1, comprising at least one of the elements selected from: W, Ti and
Nb.
3. The component for turbocharger applications as claimed in claim
1, comprising at least one of the elements selected from: C, W, Cr,
Mn, Ti, V, Nb and Si.
4. The component for turbocharger applications as claimed in claim
1, comprising substantially the following elements: C: 0.1 to 0.5%
by weight, in particular 0.25 to 0.4% by weight, Cr: 15 to 22% by
weight, in particular 18 to 20% by weight, Mn: .ltoreq.1.3% by
weight, in particular .ltoreq.1% by weight, Si: 0.8 to 2.1% by
weight, in particular 1 to 1.8% by weight, Nb: 0.4 to 1.3% by
weight, in particular 0.6 to 1.1% by weight, Ti: 0.2 to 0.6% by
weight, in particular 0.3 to 0.5% by weight, W: 1.8 to 3.0% by
weight, in particular 2 to 2.7% by weight, V: 0.3 to 1.0% by
weight, in particular 0.5 to 0.8% by weight, N: .ltoreq.3% by
weight, in particular .ltoreq.2% by weight, and Fe: ad 100% by
weight.
5. The component for turbocharger applications as claimed in claim
1, wherein it is substantially free of sigma phases.
6. The component for turbocharger applications as claimed in claim
1, wherein the component is at least one of a kinematics component,
a wastegate component and a VTG component.
7. An exhaust-gas turbocharger in particular for diesel engines,
comprising at least one component consisting of an iron-based alloy
having a ferritic base structure comprising a carbide and nitride
structure.
8. The exhaust-gas turbocharger as claimed in claim 7, wherein the
component comprises at least one of the elements selected from: W,
Ti and Nb.
9. The exhaust-gas turbocharger as claimed in claim 7, wherein the
component comprises substantially the following elements: C: 0.1 to
0.5% by weight, in particular 0.25 to 0.4% by weight, Cr: 15 to 22%
by weight, in particular 18 to 20% by weight, Mn: .ltoreq.1.3% by
weight, in particular .ltoreq.1% by weight, Si: 0.8 to 2.1% by
weight, in particular 1 to 1.8% by weight, Nb: 0.4 to 1.3% by
weight, in particular 0.6 to 1.1% by weight, Ti: 0.2 to 0.6% by
weight, in particular 0.3 to 0.5% by weight, W: 1.8 to 3.0% by
weight, in particular 2 to 2.7% by weight, V: 0.3 to 1.0% by
weight, in particular 0.5 to 0.8% by weight, N: .ltoreq.3% by
weight, in particular .ltoreq.2% by weight, and Fe: ad 100% by
weight.
10. The exhaust-gas turbocharger as claimed in claim 7, wherein the
component is substantially free of sigma phases.
11. The component for turbocharger applications as claimed in claim
1, wherein the component is a VTG component and/or a flap mount
part.
12. The exhaust-gas turbocharger as claimed in claim 7, wherein the
component comprises at least one of the elements selected from: C,
W, Cr, Mn, Ti, V, Nb and Si.
Description
[0001] The invention relates to a component for turbocharger
applications, in particular in a diesel engine, as per the preamble
of claim 1, and also to an exhaust-gas turbocharger comprising a
component as per the preamble of claim 7.
[0002] Exhaust-gas turbochargers are systems intended to increase
the power of piston engines. In an exhaust-gas turbocharger, the
energy of the exhaust gases is used to increase the power. The
increase in power is a result of the increase in the throughput of
mixture per working stroke.
[0003] A turbocharger consists essentially of an exhaust-gas
turbine with a shaft and a compressor, wherein the compressor
arranged in the intake tract of the engine is connected to the
shaft and the blade wheels located in the casing of the exhaust-gas
turbine and the compressor rotate. In the case of a turbocharger
having a variable turbine geometry, adjusting blades are
additionally mounted rotatably in a blade bearing ring and are
moved by means of an adjusting ring arranged in the turbine casing
of the turbocharger.
[0004] Extremely high demands are made on the material of the
components of a turbocharger, and in particular of the kinematics
components or of the wastegate components thereof, or, in the case
of a VTG turbocharger, also of the VTG components thereof. The
material of these components has to be heat-resistant, i.e. it
still has to afford sufficient strength and therefore dimensional
stability even at very high temperatures of up to about 900.degree.
C. Furthermore, the material has to have a high resistance to wear
and also appropriate oxidation resistance, so that the corrosion or
wear on the material is reduced even at the high operating
temperatures of several hundred .degree. C., and therefore the
resistance of the material remains ensured under the extreme
operating conditions.
[0005] DE 10 2004 062 564 A1 discloses a blade bearing ring for a
turbocharger having good thermal stability and low sliding wear. In
this type of blade bearing ring, use is made of an austenitic
material, an iron-based alloy which has a high sulfur content for
improving the lubricating action of the component. Owing to the
specific composition, the creep resistance of the material is
increased and therefore an increased dimensional stability of the
blade bearing ring is achieved at temperatures of above 850.degree.
C.
[0006] In view of this, it is an object of the present invention to
provide a component for turbocharger applications as per the
preamble of claim 1 and also a turbocharger as per the preamble of
claim 7, which have an improved temperature and oxidation
resistance and therefore also a very good dimensional stability and
high-temperature strength, and also corrosion resistance, are
distinguished by optimum tribological properties and additionally
show a reduced susceptibility to wear.
[0007] The object is achieved by the features of claim 1 and of
claim 7.
[0008] An improved temperature resistance of the material and in
particular improved sliding wear properties and a reduced tendency
toward oxidation are achieved by the embodiment according to the
invention, in the form of a component for turbocharger applications
or of an exhaust-gas turbocharger comprising such a component,
consisting of an iron-based alloy having a ferritic base structure
which comprises a carbide and nitride structure. Within the context
of the invention, a carbide structure or nitride structure is
understood to mean in this case a microstructural carbide
precipitation phase or nitride precipitation phase which is formed
in the grain and at the grain boundaries of the iron-based alloy.
The carbide structure is, in particular, a dendritic
microstructure, as a result of which a very good resistance of the
material and therefore of the component to deformation and wear is
also obtained. Provision is therefore made of a component for
turbocharger applications, or an exhaust-gas turbocharger which
comprises at least one component according to the invention, which
has an optimum temperature resistance up to 900.degree. C., also
has a high high-temperature strength, has a high wear and corrosion
resistance and is distinguished in addition by very good sliding
properties with a reduced tendency toward oxidation, in particular
at the high operating temperatures. Furthermore, the component
according to the invention and therefore the exhaust-gas
turbocharger according to the invention are also dimensionally
stable in long-term operation.
[0009] Without being bound to theory, it is assumed that the
presence of carbide precipitations and also nitride precipitations
in the ferritic iron-based alloy considerably increases the
stability of the alloy material and therefore the stability of the
component, in particular to friction wear, and also the
high-temperature strength thereof on account of this unique
structure.
[0010] By way of example, the iron-based alloy according to the
invention, i.e. the ferritic iron-based material having a carbide
and nitride structure which forms the component, is distinguished
by a maximum sliding wear rate of 0.08 mm in diameter given a
contact pressure of 20 MPa, a sliding speed of 0.0025 m/s, a
component temperature of about 850.degree. C. and 2 000 000 cycles,
i.e. an extraordinary resistance to friction wear. In addition, the
high-temperature strength, the dimensional stability and also the
high-temperature performance are also improved.
[0011] The dependent claims relate to advantageous developments of
the invention.
[0012] Thus, in one embodiment, the wear properties of the
component, i.e. specifically the resistance thereof to friction
wear, can be improved considerably by the use of at least one of
the elements tungsten (W), titanium (Ti) and niobium (Nb) in the
ferritic iron-based alloy from which the component according to the
invention is formed. The elements W, Ti and Nb substantially form
the carbide formations in the iron-based alloy, which, in addition
to the very good wear performance, also increases the corrosion
resistance of the material and therefore of the component according
to the invention.
[0013] In a further embodiment, the component according to the
invention for turbocharger applications is distinguished by the
fact that it comprises at least one of the elements selected from:
C, W, Cr, Mn, Ti, V, Nb and Si. The presence of at least one of
these elements is to be understood as meaning that such an element
or a combination of these elements is used to produce the
iron-based alloy, which is then processed to form the component
according to the invention. The elements added to the iron-based
alloy can be present here in their original form, i.e. in elemental
form, for example in the form of inclusions or precipitation
phases, or else in the form of derivatives thereof, i.e. in the
form of a compound of the corresponding element, e.g. as a metal
carbide or metal nitride, which form either during the production
of the iron-based alloy or else when forming the component
according to the invention which is produced therefrom. The
presence of the elements can be detected directly in this case in
the component according to the invention by conventional analytical
methods.
[0014] The element carbon serves here primarily for forming the
carbide structure according to the invention, i.e. the carbidic
precipitation phases, and therefore improves the strength of the
material and also the high-temperature strength thereof, and
therefore of the component according to the invention for
turbocharger applications. The element tungsten, too, mostly as a
result of the formation of carbidic structures, increases the
high-temperature strength and wear resistance of the material and
contributes to the toughness thereof. A combination of tungsten
with chromium and/or molybdenum, in particular, makes it possible
to considerably improve the corrosion resistance of the material in
acid media, and also the hot corrosion performance. The use of
chromium here increases the high-temperature tensile strength and
the scaling resistance of the material. Chromium is additionally a
strong carbide former, and therefore the wear properties of the
material, and therefore of the component according to the
invention, are also optimized thereby. The use of the element
chromium in the iron-based alloy from which the component according
to the invention for turbocharger applications is formed has yet
another advantage: under the action of high exhaust-gas
temperatures on the component, the chromium forms a Cr.sub.2O.sub.3
surface layer, i.e. an oxidic surface layer on the component, which
efficiently promotes the resistance of the component to sliding
friction and friction wear under thermal loading. The use of
manganese has a deoxidizing effect. It expands the gamma region of
the iron-based alloy and increases the yield strength and tensile
strength of the material. In addition, manganese promotes the wear
resistance of the component, in particular at high operating
temperatures. Vanadium refines the primary grain of the iron-based
alloy during the production thereof and therefore refines the cast
structure thereof. This achieves a high degree of grain refinement,
which promotes the homogeneity of the iron-based alloy and permits
a higher dynamic contact pressure of the material. In the
iron-based alloy which forms the component according to the
invention, the element niobium acts as a carbide former and
therefore promotes the carbide structure in the grain and at the
grain boundaries of the iron-based alloy. Niobium also increases
the high-temperature strength and the fatigue strength of the
material, and therefore also of the component according to the
invention for turbocharger applications. Niobium furthermore
promotes the ferrite formation and reduces the gamma region of the
iron-based alloy, and can therefore be used in a regulative
capacity. Silicon promotes the casting properties of the iron-based
alloy by reducing the viscosity of the melt during casting. In
addition, silicon in the material according to the invention
promotes deoxidation, and therefore the addition of this element to
the alloy decisively improves the resistance to hot corrosion. By
suitably selecting and combining the elements, the properties of
the iron-based alloy can therefore be controlled in a targeted
manner, such that the component according to the invention for
turbocharger applications and therefore also the exhaust-gas
turbocharger according to the invention have a particularly
balanced profile of properties. Further elements, and also
compounds, can be introduced into the iron-based alloy.
[0015] According to a further embodiment, the component according
to the invention for turbocharger applications is distinguished by
the fact that it comprises substantially the elements carbon (C)
with 0.1 to 0.5% by weight, in particular with 0.25 to 0.4% by
weight, chromium (Cr) with 15 to 22% by weight, in particular with
18 to 20% by weight, manganese (Mn) with at most 1.3% by weight, in
particular with at most 1% by weight, silicon (Si) with 0.8 to 2.1%
by weight, in particular with 1 to 1.8% by weight, niobium (Nb)
with 0.4 to 1.3% by weight, in particular with 0.6 to 1.1% by
weight, titanium (Ti) with 0.2 to 0.6% by weight, in particular
with 0.3 to 0.5% by weight, tungsten (W) with 1.8 to 3.0% by
weight, in particular with 2 to 2.7% by weight, vanadium (V) with
0.3 to 1.0% by weight, in particular with 0.5 to 0.8% by weight,
nitrogen (N) with at most 3% by weight, in particular with at most
2% by weight, and iron (Fe) as the remainder. The indications of
quantity in each case relate here to the overall weight of the
iron-based alloy from which the component according to the
invention is formed. As already stated, the presence of said
elements is to be understood as meaning that they can be present
both in elemental form and also in the form of one of the compounds
thereof in the iron-based alloy, and therefore in the component
according to the invention for turbocharger applications. In this
embodiment, substantially the aforementioned elements are present
in the component according to the invention in the quantities
indicated. This means that unavoidable impurities may be present,
although these preferably make up less than 2% by weight and in
particular less than 1% by weight, based on the overall weight of
the iron-based alloy. The unavoidable residues or impurities in
this case comprise, for example, aluminum (Al), nickel (Ni),
zirconium (Zr), cerium (Ce), boron (B), phosphorus (P) and sulfur
(S). The quantities of the individual elements can in this case be
detected directly in the component according to the invention by
means of conventional elemental analysis methods.
[0016] It has surprisingly been found that precisely the described
combination provides a material, i.e. an iron-based alloy, which,
when it is processed to form a component for turbocharger
applications, provides said component with a particularly balanced
profile of properties. This composition according to the invention
provides a component which has a particularly high high-temperature
strength, a temperature resistance up to 900.degree. C. and
therefore dimensional stability at a high temperature, and which is
distinguished by outstanding sliding properties and therefore
particularly low sliding wear. In addition, the corrosion
resistance and oxidation resistance are maximized, in particular at
high operating temperatures, as act during operation of a
turbocharger on the corresponding component.
[0017] A material which is produced in this way and from which the
component according to the invention is formed thus has the
following properties:
TABLE-US-00001 Mechanical property Value Measurement process
Tensile strength R.sub.m >650 MPa ASTM E 8M/EN 10002- 1; at
elevated temp.: EN 10002-5 Yield strength R.sub.p 0.2 >270 MPa
Standard process Elongation at break >12% Standard process
Hardness 225-265 HB ASTM E 92/ISO 6507-1 Coefficient of linear
10.5-14 K.sup.-1 Standard process expansion (20 to 900.degree.
C.)
[0018] According to a further embodiment of the invention, the
component for turbocharger applications is substantially free of
sigma phases. This applies in particular to the operation of the
component according to the invention up to 900.degree. C. This
effectively counteracts embrittlement of the material, as a result
of which the durability of the component is increased. Sigma phases
are brittle, intermetallic phases of high hardness. They arise when
a body-centered cubic metal and a face-centered cubic metal, whose
atomic radii match with only a slight discrepancy, strike one
another. Sigma phases of this type are undesirable since they have
an embrittling effect and also because of the property of the iron
matrix to withdraw chromium. The iron-based alloy according to the
invention and therefore also the component according to the
invention are substantially free of sigma phases, such that the
undesirable effects described here fail to appear. The reduction in
or prevention of the formation of sigma phases is controlled, in
particular, by a targeted selection of the elements of the
iron-based alloy, and in particular is achieved in that the silicon
content in the alloy material is at most 2.1% by weight and
preferably at most 1.8% by weight, based in each case on the
overall weight of the iron-based alloy.
[0019] What is therefore described according to the invention is a
component for turbocharger applications which is distinguished by
an outstanding wear performance, i.e. a high sliding wear
resistance even at high temperatures of up to 900.degree. C., a
high high-temperature strength and also dimensional stability and
furthermore by an excellent oxidation resistance and corrosion
resistance. By virtue of these outstanding properties, the
component according to the invention is suitable in particular for
those components for turbocharger applications which are exposed to
high temperatures of up to 900.degree. C. and/or high levels of
friction. Exemplary components comprise kinematics components,
wastegate components and VTG components, and in particular VTG
components and flap mount parts.
[0020] The iron-based alloy can be produced and processed to form
the component according to the invention for turbocharger
applications by means of conventional processes. To ensure
dimensional stability, age-annealing can be carried out at
900.degree. C. for about 2 hours, with subsequent air cooling, in
order to generate secondary precipitations. The material can be
welded by means of TIG, plasma and EB welding processes.
[0021] As an object which can be dealt with independently, claim 7
defines an exhaust-gas turbocharger comprising at least one
component, as already described, which consists of an iron-based
alloy having a ferritic base structure and comprises a carbide and
nitride structure.
[0022] The advantageous embodiments of the component according to
the invention are also applicable in the embodiments of the
exhaust-gas turbocharger according to the invention.
[0023] FIG. 1 shows a perspective view, shown partially in section,
of an exhaust-gas turbocharger according to the invention. FIG. 1
shows a turbocharger 1 according to the invention, which has a
turbine casing 2 and a compressor casing 3 which is connected to
the latter via a bearing casing 28. The casings 2, 3 and 28 are
arranged along an axis of rotation R. The turbine casing is shown
partially in section in order to illustrate the arrangement of a
blade bearing ring 6 and a radially outer guide grate 18, which is
formed by said ring and has a plurality of adjusting blades 7 which
are distributed over the circumference and have rotary axles 8. In
this way, nozzle cross sections are formed which, depending on the
position of the adjusting blades 7, are larger or smaller and act
to a greater or lesser extent upon the turbine rotor 4, positioned
in the center on the axis of rotation R, with the exhaust gas from
an engine, said exhaust gas being supplied via a supply duct 9 and
discharged via a central connection piece 10, in order to drive a
compressor rotor 17 seated on the same shaft using the turbine
rotor 4.
[0024] In order to control the movement or the position of the
adjusting blades 7, an actuating device 11 is provided. This may be
designed in any desired way, but a preferred embodiment has a
control casing 12 which controls the control movement of a tappet
member 14 fastened to it, in order to convert the movement of said
tappet member on an adjusting ring 5, located behind the blade
bearing ring 6, into a slight rotational movement of the latter. A
free space 13 for the adjusting blades 7 is formed between the
blade bearing ring 6 and an annular part 15 of the turbine casing
2. So that this free space 13 can be ensured, the blade bearing
ring 6 has spacers 16.
EXAMPLE
[0025] Unless specified otherwise, the indications of quantity of
the individual elements relate in each case to the overall weight
of the iron-based alloy.
[0026] An iron-based alloy from which a plurality of components
according to the invention for turbocharger applications,
specifically flap shaft, flap plate and bush, were formed was
produced from the following elements by a common process. The
chemical analysis yielded the following values for the elements: C:
0.25 to 0.4% by weight, Cr: 18 to 20% by weight, Mn: less than 1%
by weight, Si: 1 to 1.8% by weight, Nb: 0.6 to 1.1% by weight, Ti:
0.3 to 0.5% by weight, W: 2 to 2.7% by weight, V: 0.5 to 0.8% by
weight, N: .ltoreq.3% by weight, and Fe as the remainder. In
addition, unavoidable residues of Al, Ni, Zr, Ce, B, P and S were
found in traces with a proportion of less than 1% by weight.
[0027] The components produced in accordance with this example were
distinguished by the following properties:
TABLE-US-00002 Measured value Property (measurement process)
Tensile strength R.sub.m at 20.degree. C. 655 MPa (ASTM E 8M/EN
10002-1) Yield strength R.sub.p 0.2 at 20.degree. C. 277 MPa
(standard process) Elongation at break 13.5% (standard process)
Hardness 248 HB (ASTM E 92/ISO 6507-1) Coefficient of linear
expansion at 20.degree. C. 12.6 K.sup.-1 (standard process)
High-temperature strength R.sub.m at 900.degree. C. 123 MPa (EN
10002-5) High-temperature strength R.sub.m at 800.degree. C. 188
MPa (EN 10002-5) High-temperature strength R.sub.m at 700.degree.
C. 257 MPa (EN 10002-5) High-temperature strength R.sub.m at
600.degree. C. 333 MPa (EN 10002-5) High-temperature strength
R.sub.m at 500.degree. C. 395 MPa (EN 10002-5) High-temperature
strength R.sub.m at 400.degree. C. 443 MPa (EN 10002-5) Yield
strength R.sub.p 0.2 at 900.degree. C. 83 MPa (standard process)
Yield strength R.sub.p 0.2 at 800.degree. C. 115 MPa (standard
process) Yield strength R.sub.p 0.2 at 700.degree. C. 174 MPa
(standard process) Yield strength R.sub.p 0.2 at 600.degree. C. 229
MPa (standard process) Yield strength R.sub.p 0.2 at 500.degree. C.
281 MPa (standard process) Yield strength R.sub.p 0.2 at
400.degree. C. 360 MPa (standard process)
[0028] The material was subjected to a validation test series which
comprised the following tests: [0029] Open-air weathering test
[0030] Climate change test [0031] Thermal shock test/cycle
test--300 h [0032] Hot-gas corrosion test in a cracking furnace
[0033] Strauss test according to DIN EN ISO 3651-2 [0034] Vibration
friction wear test on a tribometer: bush/shaft at operating
temperature (900.degree. C.)
[0035] The respective component was distinguished in all tests by
an outstanding resistance to the acting forces. The material
therefore had an extremely high wear resistance and outstanding
oxidation resistance, such that corrosion and wear/friction wear to
the material were reduced considerably under the indicated
conditions, and therefore the resistance of the material and
therefore also of the component formed therefrom also remained
ensured over a long time.
Thermal Cycle Test:
[0036] The components (shaft/bush) according to the invention were
subjected to a thermal cycle test, in which the thermal shocks were
carried out as follows: [0037] 1. use of stationary rotors; [0038]
2. 2-EGT operation; [0039] 3. test duration: 350 h (approximately
2000 cycles); [0040] 4. throughout the test, the exhaust-gas flap
of the EGTs remains open by 15'; [0041] 5. high temperature: rated
power point T3=750.degree. C., mass flow EGT on the turbine side:
0.5 kg/s; [0042] 6. low temperature: T3=100.degree. C., mass flow
EGT on the turbine side: 0.5 kg/s; [0043] 7. cycle duration:
2.times.5 min. (10 min.); [0044] 8. three intermediate crack tests
are carried out.
[0045] Given the following load collective, the respective
component (shaft/bush) according to the invention was distinguished
by a low high-temperature oxidation, i.e. an oxidation rate of at
most 40 .mu.m, in particular of at most 35 .mu.m, at a component
temperature of 900.degree. C.:
TABLE-US-00003 Parameter Result Bearing load 10-18 N/mm.sup.2
Sliding speed 0.0025 m/s Component temperature 500-900.degree. C.
Surface roughness Rz 6.3 Test medium Diesel exhaust gas Test
duration 500 h Clock frequency 0.2 Hz Adjustment angle 45.degree.
Friction value <0.18 Journal diameter 4.7 mm Pressure pulsation
>200 bar Exhaust-gas pressure 1.5 bar Wear rate <0.08 mm
[0046] The results indicated here verify that the component
according to the invention is ideally suited for turbocharger
applications in a temperature range of up to 900.degree. C.
LIST OF REFERENCE SIGNS
[0047] 1 Turbocharger [0048] 2 Turbine casing [0049] 3 Compressor
casing [0050] 4 Turbine rotor [0051] 5 Adjusting ring [0052] 6
Blade bearing ring [0053] 7 Adjusting blades [0054] 8 Pivot axles
[0055] 9 Supply duct [0056] 10 Axial connection piece [0057] 11
Actuating device [0058] 12 Control casing [0059] 13 Free space for
guide blades 7 [0060] 14 Tappet member [0061] 15 Annular part of
the turbine casing 2 [0062] 16 Spacer/spacer cam [0063] 17
Compressor rotor [0064] 18 Guide grate [0065] 28 Bearing casing
[0066] R Axis of rotation
* * * * *