U.S. patent application number 13/942134 was filed with the patent office on 2013-11-14 for turbine cleaning.
The applicant listed for this patent is ABB Turbo Systems AG. Invention is credited to Martin Eckert, William Gizzi, Gerd Mundinger, Joel Schlienger.
Application Number | 20130298944 13/942134 |
Document ID | / |
Family ID | 45476520 |
Filed Date | 2013-11-14 |
United States Patent
Application |
20130298944 |
Kind Code |
A1 |
Mundinger; Gerd ; et
al. |
November 14, 2013 |
TURBINE CLEANING
Abstract
A cleaning method is disclosed for wet cleaning of an
exhaust-gas turbine. An amount of cleaning fluid injected via a
nozzle into the flow duct of the turbine can be variable over a
course of time about a defined mean amount of cleaning fluid.
Inventors: |
Mundinger; Gerd; (Wettingen,
CH) ; Schlienger; Joel; (Zurich, CH) ; Gizzi;
William; (Birmensdorf, CH) ; Eckert; Martin;
(Gorwihl, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ABB Turbo Systems AG |
Baden |
|
CH |
|
|
Family ID: |
45476520 |
Appl. No.: |
13/942134 |
Filed: |
July 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2012/050325 |
Jan 11, 2012 |
|
|
|
13942134 |
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Current U.S.
Class: |
134/18 ; 134/113;
134/169C; 134/22.12 |
Current CPC
Class: |
F01D 25/002 20130101;
F05D 2220/40 20130101 |
Class at
Publication: |
134/18 ;
134/22.12; 134/169.C; 134/113 |
International
Class: |
F01D 25/00 20060101
F01D025/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 14, 2011 |
DE |
10 2011 008 649.8 |
Claims
1. A cleaning method for cleaning a turbine which is impinged on by
exhaust gases conducted in a flow duct to a rotor blade of a
turbine wheel, the method comprising: injecting, in a cleaning
cycle, a cleaning fluid via at least one nozzle into the flow duct;
and varying an amount of the cleaning fluid injected, per nozzle,
into the flow duct of the turbine over a time of the cleaning cycle
and about a defined mean fluid amount, wherein through the varying
of the amount of cleaning fluid, a distribution of cleaning fluid
and a wetting of surfaces to be cleaned will be varied in a
transient manner over an adjustable surface region.
2. The cleaning method as claimed in claim 1, comprising:
specifying the defined mean fluid amount based on geometric
dimensions of the turbine.
3. The cleaning method as claimed in claim 1, comprising:
specifying the defined mean fluid amount as a function of
conditions prevailing in the flow duct upstream of the turbine by:
measuring at least one measurement variable which characterizes
conditions prevailing upstream of the turbine, determining a value
for the defined mean fluid amount from the measured measurement
variable, and varying injection of the cleaning fluid about the
defined mean fluid amount over the time of the cleaning cycle.
4. The cleaning method as claimed in claim 3, comprising: measuring
measurement variables of an associated internal combustion engine
to determine the conditions prevailing in the flow duct upstream of
the turbine.
5. The cleaning method as claimed in claim 3, comprising: measuring
measurement variables of the exhaust-gas turbocharger to determine
the conditions prevailing in the flow duct upstream of the
turbine.
6. The cleaning method as claimed in claim 1, comprising: injecting
a cleaning fluid into the flow duct via two or more nozzles
arranged in a manner distributed along a circumference, wherein an
amount of cleaning fluid injected, per individual nozzle, into the
flow ducts of the turbine is varied over a time of the cleaning
cycle about a defined mean fluid amount, such that an overall fluid
amount from all the nozzles over the time of the cleaning cycle
remains constant and corresponds to the defined mean fluid amount
multiplied by the number of nozzles.
7. The cleaning method as claimed in claim 1, comprising:
controlling an amount of cleaning fluid injected, per nozzle, into
the flow duct by varying an injection pressure of the cleaning
fluid.
8. The cleaning method as claimed in claim 1, comprising:
controlling an amount of cleaning fluid injected, per nozzle, into
the flow duct by way of nozzle geometry.
9. The cleaning method as claimed in claim 1, comprising: varying
an amount of cleaning fluid injected, per nozzle, into the flow
duct periodically.
10. The cleaning method as claimed in claim 9, wherein a period
duration is between 3 and 120 seconds.
11. A cleaning device for cleaning a turbine which will be impinged
on by exhaust gases during operation, comprising: a pump for
delivering a cleaning fluid; at least one nozzle for injecting the
cleaning fluid into a flow duct of a turbine; and at least one
adjustable element for dynamically varying a throughflow of the
cleaning fluid injected, per nozzle, into the flow duct of a
turbine over a time of the cleaning cycle and about a defined mean
fluid amount, wherein through the varying of the amount of cleaning
fluid, a distribution of cleaning fluid and a wetting of surfaces
to be cleaned will be varied in a transient manner over an
adjustable surface region.
12. The cleaning device as claimed in claim 11, wherein the
adjustable element comprises: a pump for delivering cleaning fluid
with an adjustable throughflow rate.
13. The cleaning device as claimed in claim 11, wherein the
adjustable element comprises: an adjustable valve in the feed line
for providing cleaning fluid to the nozzles.
14. The cleaning device as claimed in claim 11, comprising: two or
more nozzles , wherein the adjustable element includes an
adjustable flow distributor in the feed line for providing cleaning
fluid to the nozzles.
15. The cleaning device as claimed in claim 11, wherein the
adjustable element includes at least one nozzle with at least one
of: an adjustable nozzle opening, a regulated iris aperture, or an
oscillating nozzle opening flap.
16. The cleaning device as claimed in claim 11, wherein the
adjustable element includes an oscillating flow element in the feed
line to the at least one nozzle.
17. The cleaning method as claimed in claim 3, comprising:
controlling an amount of cleaning fluid injected, per nozzle, into
the flow duct by varying an injection pressure of the cleaning
fluid.
18. The cleaning method as claimed in claim 3, comprising:
controlling an amount of cleaning fluid injected, per nozzle, into
the flow duct by way of nozzle geometry.
19. The cleaning method as claimed in claim 3, comprising: varying
an amount of cleaning fluid injected, per nozzle, into the flow
duct periodically.
20. A cleaning device as claimed in claim 11 for cleaning a
turbine, in combination with the turbine and an internal combustion
engine configured such that the turbine will be impinged on by
exhaust gases of the internal combustion engine during operation,
the combination comprising: means for measuring measurement
variables of the internal combustion engine to determine conditions
prevailing in the flow duct upstream of the turbine.
Description
RELATED APPLICATION(S)
[0001] This application claims priority as a continuation
application under 35 U.S.C. .sctn.120 to PCT/EP2012/050325, which
was filed as an International Application on Jan. 11, 2012
designating the U.S., and which claims priority to German
Application 102011008649.8 filed in Germany on Jan. 14, 2011. The
entire contents of these applications are hereby incorporated by
reference in their entireties.
FIELD
[0002] The present disclosure relates to the field of turbomachines
impinged on by exhaust gases of internal combustion engines. A
cleaning method is disclosed for cleaning of an exhaust-gas turbine
and a cleaning device is disclosed for cleaning of a turbine, which
is impinged on by exhaust gases of an internal combustion
engine.
BACKGROUND INFORMATION
[0003] Exhaust-gas turbines are used in exhaust-gas turbochargers
for supercharging of internal combustion engines, or in power
turbines for converting energy contained in the exhaust gases of
internal combustion engines into mechanical or electrical
energy.
[0004] Depending on the specific operating situation and the
composition of the fuels used for driving the internal combustion
engine, fouling of the turbine blades of the rotor, of the guide
blades of the nozzle ring and of the various turbine housing parts
occurs sooner or later in the exhaust-gas turbine.
[0005] Such dirt accumulations can lead, in the region of the
nozzle ring, to decreased turbine efficiency, and accordingly to a
reduction in the performance of the downstream machines, for
example of the compressor driven by the exhaust-gas turbine, and of
the supercharged internal combustion engine itself. As a result,
there is an increase in the exhaust-gas temperatures in the
combustion chamber, by which both the internal combustion engine
and also the turbocharger may be thermally overloaded. In the
internal combustion engine, it may be the case for example that the
outlet valves are damaged or even destroyed.
[0006] If a layer of dirt accumulates on the nozzle ring and on the
turbine blades of a turbocharger connected to a four-stroke
internal combustion engine, an increase of the turbocharger
rotational speed and consequently of the charge pressure and of the
cylinder pressure should be expected. This can result in components
of both the internal combustion engine and also of the turbocharger
being subjected not only to the increased thermal loading but also
to increased mechanical loading, which may likewise lead to
destruction of the components concerned.
[0007] In the case of an irregular distribution of a layer of dirt
on a circumference of rotor blades of a turbine wheel, an imbalance
of the rotor increases, whereby a bearing arrangement may also be
damaged.
[0008] If, on the turbine housing, dirt accumulations occur on the
outer contour of a flow duct running in the region radially outside
the turbine blades, contact can occur during operation owing to
reduced radial clearance between the turbine blades and turbine
housing, which contact can damage the turbine blades and, in an
extreme case, render them unusable.
[0009] It is therefore desireable for dirt adhering to the nozzle
ring, turbine blades and affected regions of the turbine housing to
be regularly removed during operation. This has been addressed
through use of dry or wet cleaning systems.
[0010] Wet cleaning systems are characterized in that, during a
cleaning cycle, a liquid cleaning medium, for example cold water,
is injected by one or more nozzles positioned on the turbine inlet
side. As a result of the introduction of cold cleaning fluid onto
hot dirt accumulations, the latter can be removed and surfaces can
be restored to nearly their original state upon initial delivery.
The injection of cold cleaning fluid onto the hot turbine
components however subjects the turbine components to relatively
high thermal and mechanical loading.
[0011] To address resulting damage to the components of the
turbine, the turbine wet cleaning has been used at low engine
loads--with correspondingly low gas inlet temperatures at the
turbocharger. The cleaning cycle has therefore been configured such
that the load of the engine is reduced to a level suitable for the
cleaning cycle (for example to 25% of the normal engine load) and,
after a waiting time, cleaning fluid is injected over a defined
time period (for example 10 minutes). Subsequently, during a
further time period (for example 10 minutes), any cleaning fluid
still present in the turbocharger is evaporated, before the engine
is subsequently returned to its normal load level.
[0012] The injection of cleaning fluid through one or more nozzles
upstream of the turbine inlet during the cleaning cycle can take
place at constant pressure and with a constant throughflow rate.
The injection nozzles are configured so as to realize a
distribution of cleaning fluid which, per nozzle, can wet a certain
surface region of the nozzle ring or of the turbine housing with
cleaning fluid. The impinging distribution of cleaning fluid on the
surfaces can be dependent on multiple factors such as the flow
state upstream of the turbine, the jet shape generated by the
nozzle opening of the nozzles, the injection pressure and amount of
cleaning fluid, the turbine inlet temperature, and so forth.
[0013] The nozzles can be configured for a defined load point,
known flow variables and constant cleaning system variables. During
real engine operation, the above-mentioned influential variables
may deviate significantly from the variables used in the original
configuration, which in turn changes and even reduces in size the
surface regions wetted during real operation, which can lead to
unsatisfactory cleaning results.
[0014] The time at which a cleaning cycle should be initiated may
either be made fixedly dependent on the operating duration, for
example fixed cleaning intervals after a certain number of
operating hours, or fouling indicators may be detected which then
can automatically trigger a cleaning cycle.
[0015] DE 35 15 825 A1 discloses a method and a device for cleaning
of the rotor blades and of the nozzle ring of an axial turbine of
an exhaust-gas turbocharger. The cleaning device is composed of a
plurality of nozzles arranged on the gas inlet housing of the axial
turbine, which nozzles extend into the flow duct, and a feed line
for cleaning fluid.
[0016] When a certain level of fouling of the axial turbine is
reached, a cleaning demand is determined by a measurement and
evaluation unit. Accordingly, cleaning fluid is injected into the
flow duct via nozzles arranged upstream of the guide blades. The
droplets generated are transported by the exhaust-gas flow to the
guide and rotor blades of the axial turbine, and clean them by
removing the adherent dirt accumulations therefrom.
[0017] A relatively large amount of cleaning fluid (approximately
3-5 1/min of cleaning fluid per m.sup.3/s of exhaust gas) is fed
into the flow during a relatively short cleaning interval in order
to attain the most thorough cleaning possible. In the cleaning
method, owing to the large amount of cleaning fluid, the engine
load should be reduced early and during the entire cleaning
process. This can avoid an inadmissibly large increase in
exhaust-gas temperatures during the cleaning process. An excessive
increase of the exhaust-gas temperatures during the cleaning
process will lead to thermal overloading of the exhaust-gas
turbines and of the internal combustion engine.
[0018] It is also known that, in the initial phase of the injection
of a cold cleaning fluid in large amounts (cf. above) onto the hot
guide blades of the nozzle ring and rotor blades of the turbine
wheel, an additional thermoshock cleaning effect can be attained.
Not only the guide blades of the nozzle ring and the rotor blades
of the turbine wheel but also the turbine housing parts are
subjected to very high thermal loading during the thermoshock
cleaning. Preventing the formation of inadmissibly high thermal
stresses or even cracks in the corresponding components is
structurally highly complex, involves sophisticated regulation of
the cleaning, and thus entails high costs.
[0019] WO 2007/036059 A1 discloses a cleaning method for the wet
cleaning of an exhaust-gas turbine, in which a small amount of
cleaning fluid is continuously or cyclically fed into the
exhaust-gas flow of an exhaust-gas turbine and conducted to the
components, which are to be cleaned, of the exhaust-gas turbine.
The small amount of cleaning fluid can be fed in during unchanged
internal combustion engine operation, such that the exhaust-gas
turbine can be cleaned, or kept clean, throughout the entire
internal combustion engine operating range. Fluctuations in the
power output of the internal combustion engine owing to an arising
desire for exhaust-gas turbine cleaning should thus not occur.
Furthermore, the formation of thermal stress cracks in the turbine
housing parts at particularly high risk in this regard can be
substantially prevented.
[0020] FI 117 804 discloses a cleaning device for the wet cleaning
of an exhaust-gas turbine in which the pressure of the cleaning
fluid is statically fixed at approximately 2 bar above the pressure
of the exhaust gases in the flow duct. In order that the wet
cleaning can take place at full load, a part of the relatively cool
fresh air from the compressor outlet is fed to the exhaust-gas
flow. This reduces the temperature of the exhaust-gas flow to a
predetermined value optimum for the cleaning of the turbine
parts.
[0021] EP 1972758 A1 discloses a cleaning method for the wet
cleaning of an exhaust-gas turbine, in which cleaning fluid is fed
into the exhaust-gas flow of the exhaust-gas turbine, and conducted
to the components, which are to be cleaned, of the exhaust-gas
turbine, in a manner independent of the operating point.
[0022] Here, the injection pressure of the cleaning fluid is
adapted to the conditions upstream of the exhaust-gas turbine. For
this purpose, at least one measurement variable which characterizes
the conditions prevailing upstream of the turbine is measured in a
first step, a value for the injection pressure of the cleaning
fluid is determined from the measured measurement variable in a
second step, and the cleaning fluid is injected with the determined
injection pressure into the flow duct in a third step.
SUMMARY
[0023] A cleaning method is disclosed for cleaning a turbine which
is impinged on by exhaust gases conducted in a flow duct to a rotor
blade of a turbine wheel, the method comprising: injecting, in a
cleaning cycle, a cleaning fluid via at least one nozzle into the
flow duct; and varying an amount of the cleaning fluid injected,
per nozzle, into the flow duct of the turbine over a time of the
cleaning cycle and about a defined mean fluid amount, wherein
through the varying of the amount of cleaning fluid, a distribution
of cleaning fluid and a wetting of surfaces to be cleaned will be
varied in a transient manner over an adjustable surface region.
[0024] A cleaning device is also disclosed for cleaning a turbine
which will be impinged on by exhaust gases during operation,
comprising: a pump for delivering a cleaning fluid; at least one
nozzle for injecting the cleaning fluid into a flow duct of the
turbine; and at least one adjustable element for dynamically
varying a throughflow of the cleaning fluid injected, per nozzle,
into the flow duct of the turbine over a time of the cleaning cycle
and about a defined mean fluid amount, wherein through the varying
of the amount of cleaning fluid, a distribution of cleaning fluid
and a wetting of surfaces to be cleaned will be varied in a
transient manner over an adjustable surface region.
BRIEF DESCRIPTION OF THE DRAWINGS
[0025] Exemplary cleaning methods as disclosed herein will be
described in more detail below on the basis of the Figures, in
which:
[0026] FIG. 1 is a sectional illustration of an exemplary
exhaust-gas turbocharger with an exemplary cleaning device on the
turbine side;
[0027] FIG. 2 shows a diagram of an exemplary profile with respect
to time of an amount of cleaning fluid, and a schematically
illustrated effect of a variance of an amount of cleaning fluid on
a wetting of turbine housing parts;
[0028] FIG. 3 shows two diagrams of an exemplary profile with
respect to time of injection pressure and amount of cleaning
fluid;
[0029] FIG. 4 shows a diagram of an exemplary embodiment of a
cleaning device for carrying out cleaning methods as disclosed
herein, and illustrates, a variable pump with adjustable
throughflow;
[0030] FIG. 5 shows a diagram of another exemplary embodiment of a
cleaning device for carrying out cleaning methods as disclosed
herein, and illustrates an adjustable valve in a feed line;
[0031] FIG. 6 shows a diagram of another exemplary embodiment of a
cleaning device for carrying out methods disclosed herein, and
illustrates an adjustable flow distributor;
[0032] FIG. 7 shows a diagram of another exemplary embodiment of a
cleaning device for carrying out cleaning methods disclosed herein,
and illustrates individually adjustable nozzle openings; and
[0033] FIG. 8 shows an exemplary plot of an amount of cleaning
fluid versus time profile.
DETAILED DESCRIPTION
[0034] A cleaning method is disclosed for wet cleaning of an
exhaust-gas turbine, by which optimal wetting of fouled turbine
parts can be realized (e.g., as far as possible over a full area of
the parts).
[0035] Exemplary embodiments include means for transient injection
of cleaning fluid, with an amount of cleaning fluid injected via a
nozzle into the flow duct of the turbine being variable over a
course of time about a defined mean amount of cleaning fluid.
[0036] Generation of a temporally variable amount of cleaning fluid
(e.g., periodic, aperiodic, random profile) may be realized for
example through a manipulation of injection pressure or of the
amount of cleaning fluid, for example by means of a pump with
regulable throughflow, a regulateable valve in the feed line, or
oscillating flow elements upstream of the nozzle, and/or through a
manipulation of a size of the nozzle opening, for example by means
of regulated iris apertures or regulated or freely oscillating
nozzle opening flaps. The amount of cleaning fluid can be varied
about a defined mean value, wherein the temporally variable profile
may for example optionally be periodic, aperiodic or random.
[0037] In the case of the variation of the injection pressure, for
example, the defined mean injection pressure can be specified on
the basis of, for example, the geometric dimensions of the
exhaust-gas turbine, or dynamically as a function of the respective
operating point of the exhaust-gas turbine and/or of the respective
operating point of the internal combustion engine.
[0038] The variation of the amount of cleaning fluid can, for
example, be realized by means for automatic injection pressure
regulation, or by means for regulation for the nozzle opening.
[0039] Where the injection pressure is varied in a transient
manner, the generated distribution of cleaning fluid and thus the
wetting of the turbine surfaces can vary, even with otherwise
constant cleaning system variables. An exemplary advantage, through
the variation of the amount of cleaning fluid, is that the
distribution of cleaning fluid and the surface wetting can be
varied in a transient manner over an adjustable surface region, and
an enhanced cleaning action can be attained independently of a
respective individual flow state in the turbocharger.
[0040] Optionally, the variation of the amount of cleaning fluid
may, in the case of two or more nozzles arranged so as to be
distributed along the circumference, be realized differently from
one another, such that, over the course of time, profiles of the
amounts of cleaning fluid are generated which differ from one
another, or which are offset with respect to one another in terms
of time. Here, the overall injected amount of cleaning fluid may
for example optionally be kept constant.
[0041] FIG. 1 shows a sectional illustration of an exemplary
exhaust-gas turbocharger having an exhaust-gas turbine (on the
right) and having a compressor. The exhaust-gas turbine can include
a turbine wheel 2 with rotor blades 21, which turbine wheel is
arranged in a turbine housing 20. The turbine wheel is connected to
a compressor wheel 1 by means of a shaft 3 which is rotatably
mounted in a bearing housing 30. The compressor wheel is arranged
in the compressor housing 10.
[0042] In a region of the turbine inlet, in which hot exhaust gas
flows from a collecting duct, which is for example formed as an
annular hollow chamber, through the narrow flow duct to the rotor
blades 21 of the turbine wheel 2, the turbine has a guide apparatus
(e.g., a nozzle ring with guide blades) 22 which orients the
exhaust-gas flow toward the rotor blades of the turbine wheel. The
wall parts of the turbine housing which delimit the flow duct in
this region, and the guide blades of the guide apparatus, are
subject to fouling by accumulation.
[0043] Directly upstream of the turbine inlet, the exhaust-gas
turbine has a cleaning device which has an annular duct 41 for a
supply of the cleaning fluid, and one or more nozzles 42 for
injection of the cleaning fluid into the collecting and flow duct
of the turbine.
[0044] Depending on the type of turbine (emg., axial, mixed flow or
radial turbine) and/or on a design of the turbine, an exact
arrangement of the cleaning device may vary as those skilled in the
art will appreciate. However, the nozzles are for example mounted
upstream of the guide apparatus, such that the flow of the hot
exhaust gas entrains the cleaning fluid and thus distributes it to
the surfaces to be cleaned.
[0045] The nozzles 42 can be arranged in a distributed manner along
a circumference of the turbine housing, wherein the number of
nozzles may for example be coordinated with the number of guide
blades of the guide apparatus. For example, one nozzle may be
provided for each guide blade, or one nozzle may be provided for
every two guide blades. Optionally, independently of the guide
apparatus, additional nozzles may be provided which are for example
oriented directly toward the walls of the flow duct.
[0046] If a cleaning cycle is to be initiated, owing to a certain
number of operating hours being reached or because a fouling
indicator indicates cleaning should be initiated, a cleaning fluid
can be supplied to the hot exhaust-gas flow upstream of the guide
device and of the rotor blades of the turbine wheel. Here, the
cleaning fluid, such as water or water containing a
cleaning-promoting substance, can be injected in controlled amounts
and with a defined pressure into the flow ducts.
[0047] According to exemplary embodiments, an amount and/or the
injection pressure can be varied in a transient manner, such that,
as per FIG. 2, depending on the amount and/or injection pressure,
different regions of the surfaces to be cleaned are wetted with the
cleaning fluid.
[0048] FIG. 2 schematically illustrates, for three points on an
exemplary plotted profile with respect to time "t" of the
periodically varied injection pressure "p.sub.w", an effect of the
respective injection pressure on the spray profile of the cleaning
fluid. Illustrated in the left-hand side of the Figure is a mean
injection pressure at which the jet discharged from the nozzle into
the flow is diverted by the flow toward a central region of the
guide apparatus. In the ease of higher pressure, illustrated in a
middle portion of the Figure, the jet from the nozzle reaches a
remote edge of the flow duct, whereas in the case of lower
pressure, in the right-hand figure part, only the right-hand, inner
edge regions of the guide blades are wetted.
[0049] A transient variation of an amount of cleaning fluid and/or
of the injection pressure can take place about a mean value, that
is to say about a defined mean fluid amount or a mean injection
pressure, and within a range, delimited at one side or two sides,
between a minimum value and/or a maximum value. The mean, minimum
and/or maximum values may for example be fixedly predefined on the
basis of turbine geometry and the provided flow conditions, or may
be adapted dynamically to the flow conditions upstream of the
turbine--for example, to a pulsing exhaust-gas flow--and/or to
engine load.
[0050] In the second case, it would be possible, for example at the
start of a cleaning interval, for the defined mean values to be
calculated on the basis of defined characteristic curves, or read
out from a table, as a function of one or more turbine-specific or
engine-specific measurement variables. The turbine-specific or
engine-specific measurement variables may be determined in various
ways. For example, engine-specific measurement data such as load
lever position or injection parameters may be evaluated, and the
engine load derived therefrom. If further assemblies, for example
an electrical generator, are positioned downstream of the engine,
the engine load may be measured directly at the downstream
assembly.
[0051] Specific measurement data of the turbocharger, for example
the turbocharger rotational speed, may also be evaluated. Since the
configuration of the turbocharger is normally known, it is
possible, by way of the turbocharger rotational speed and from the
corresponding characteristic maps, to approximately determine the
gas mass flow or the gas volume flow and thus the state upstream of
the turbine. It would furthermore be possible to measure the gas
flow directly in the flow duct, for example by means of, for
example, a heating wire anemometer, ultrasound anemometer or laser
Doppler anemometer. More details regarding determination of
turbine-specific or engine-specific measurement variables are
readily known to those skilled in the art and are described, for
example, in EP 1972758 A1.
[0052] A exemplary variation of an amount of cleaning fluid
m*.sub.w, and/or of an injection pressure p.sub.w may, as
schematically indicated in the diagrams of FIG. 3, take place in a
periodic (curve b, dotted), aperiodic or entirely random (curve c,
solid) manner about the mean injection pressure (curve a, dashed)
or the mean injection amount. In the case of a changing injection
pressure (upper diagram) and otherwise constant conditions, the
injected amount of cleaning fluid m*.sub.w (lower diagram) follows
the profile of the injection pressure p.sub.w.
[0053] FIG. 8 shows a further example of a periodic profile of the
injected amount of cleaning fluid m*.sub.w, in which the
instantaneous amount of cleaning fluid per nozzle temporarily
assumes the value zero within a period duration.
[0054] An exemplary cleaning cycle can include multiple periods of
in each case 3-120 s duration, wherein the overall duration of a
respective cleaning cycle may be fixedly predefined, or may be
dependent on the present fouling of the components of the turbine
and/or on the number of operating hours since a previous cleaning
cycle.
[0055] If the cleaning device includes two or more nozzles arranged
in a manner distributed along a circumference, an exemplary
cleaning method as disclosed herein can optionally be designed such
that an overall fluid amount from all of the nozzles over the
course of time within the cleaning cycle remains constant and
corresponds to the defined mean fluid amount multiplied by the
number of nozzles. By contrast, the amount of cleaning fluid
injected, per nozzle, into the flow duct of the turbine can be
varied over the course of time within the cleaning cycle about the
defined mean fluid amount.
[0056] An exemplary manner by which the temporally variable amount
of cleaning fluid per nozzle is controlled is illustrated in FIGS.
4 to 7 by way of example and schematically on the basis of various
exemplary embodiments of cleaning devices:
[0057] FIG. 4 shows an exemplary embodiment of a cleaning device
for cleaning a turbine, which is impinged on by exhaust gases of an
internal combustion engine, by way of a cleaning method as
disclosed herein, the cleaning device having a pump 431 with
adjustable throughflow. The pump may be activated by means of
control electronics 5, with or without feedback of the respectively
presently set throughflow rate.
[0058] FIG. 5 shows another exemplary embodiment of a cleaning
device, having a pump 43 which delivers a constant amount of
cleaning fluid, and having, for this purpose, a valve 44 with
adjustable throughflow in the feed line between the pump 43 and the
nozzles 42. With the FIG. 4 and FIG. 5 embodiments, multiple
nozzles 42 can he configured such that they cannot be activated
individually unless the pump and/or valve are guided adjacent one
another in duplex or multiplex configuration.
[0059] FIG. 6 shows another exemplary embodiment having a pump 43
which delivers a constant amount of cleaning fluid, and an
adjustable flow distributor 45 which, in an electronically or
mechanically controlled manner, varies the amount of cleaning fluid
conducted to the various nozzles 42. In this embodiment, it is
possible for the amount of cleaning fluid to vary individually from
nozzle to nozzle, and for the overall amount of cleaning fluid to
thus be kept constant.
[0060] This is likewise possible with an exemplary embodiment
according to FIG. 7, in which the individual nozzles 421 have
adjustable nozzle openings, for example adjustable iris apertures
or adjustable or freely oscillating nozzle opening flaps.
[0061] Those skilled in the art will appreciate that any or all of
the various features described with respect to the exemplary
embodiments discussed herein may be combined with one another
and/or with further elements for adjusting injection pressure
and/or throughflow rate.
[0062] As an alternate to the described electronically controlled
control unit, it is also possible for mechanical control means, for
example oscillating flow elements or rotating flaps, to be provided
in order to vary the throughflow through a feed line or the
distribution between the individual feed lines to the nozzles.
[0063] It will thus be appreciated by those skilled in the art that
the present invention can be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof The presently disclosed embodiments are therefore
considered in all respects to be illustrative and not restricted.
The scope of the invention is indicated by the appended claims
rather than the foregoing description and all changes that come
within the meaning and range and equivalence thereof are intended
to be embraced therein.
LIST OF REFERENCE SIGNS
[0064] 1 Compressor wheel [0065] 10 Compressor housing [0066] 2
Turbine wheel [0067] 20 Turbine housing [0068] 21 Rotor blades of
the turbine wheel [0069] 22 Guide apparatus (nozzle ring with guide
blades) [0070] 3 Shaft of the turbocharger [0071] 30 Bearing
housing [0072] 41 Duct for the supply of the cleaning fluid [0073]
42 Nozzles for the injection of the cleaning fluid [0074] 421
Nozzles with adjustable nozzle openings [0075] 43 Pump for the
cleaning fluid to be injected [0076] 431 Variable pump with
adjustable throughflow [0077] 44 Adjustable valve in the feed line
for the cleaning fluid [0078] 45 Adjustable flow distributor in the
feed line for the cleaning fluid [0079] 5 Control unit [0080]
P.sub.w Injection pressure of the cleaning fluid [0081] m*.sub.w
Amount of cleaning fluid injected [0082] a Curve profile of the
injection with constant injection pressure [0083] b Curve profile
of the injection with periodically changing injection pressure
[0084] c Curve profile of the injection with randomly changing
injection pressure [0085] t Time
* * * * *