U.S. patent application number 14/027206 was filed with the patent office on 2014-02-20 for turbine for an exhaust gas turbocharger.
This patent application is currently assigned to DAIMLER AG. The applicant listed for this patent is DAIMLER AG. Invention is credited to Nils Brinkert, Siegfried Sumser.
Application Number | 20140050568 14/027206 |
Document ID | / |
Family ID | 50100146 |
Filed Date | 2014-02-20 |
United States Patent
Application |
20140050568 |
Kind Code |
A1 |
Brinkert; Nils ; et
al. |
February 20, 2014 |
TURBINE FOR AN EXHAUST GAS TURBOCHARGER
Abstract
In a turbine for an exhaust gas turbocharger having a turbine
housing including a turbine wheel with blades, each having a
leading edge and a trailing edge, an adjusting device is provided
controlling the flow to the leading blade edges of the turbine
wheel and also a device for controlling the flow from the trailing
edges of the turbine wheel blades, both devices are coupled to one
another so as to be adjustable by a single actuator.
Inventors: |
Brinkert; Nils; (Stuttgart,
DE) ; Sumser; Siegfried; (Stuttgart, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
DAIMLER AG |
Stuttgart |
|
DE |
|
|
Assignee: |
DAIMLER AG
Stuttgart
DE
|
Family ID: |
50100146 |
Appl. No.: |
14/027206 |
Filed: |
September 15, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
PCT/EP2011/008095 |
Dec 6, 2011 |
|
|
|
14027206 |
|
|
|
|
Current U.S.
Class: |
415/148 |
Current CPC
Class: |
F01D 7/00 20130101; F05D
2220/40 20130101; F01D 17/14 20130101; F02C 6/12 20130101 |
Class at
Publication: |
415/148 |
International
Class: |
F01D 7/00 20060101
F01D007/00 |
Foreign Application Data
Date |
Code |
Application Number |
Mar 19, 2011 |
DE |
10 2011 014 458.7 |
Claims
1. A turbine (32) for an exhaust gas turbocharger (22), having a
turbine housing (76), a turbine wheel (74) accommodated in the
turbine housing (76) and being rotatable about a rotational axis
(73), the turbine wheel having blades (82) each with a leading edge
(90) and a trailing edge (96, 102) and being driven by exhaust gas
flowing from the turbine housing (76) to the turbine wheel (74) and
reaching the turbine wheel blade at the leading edge (90) and
leaving the turbine wheel blade via the trailing edge (96, 102), an
adjusting device (56) movable between a first position in which the
trailing edge (96, 102) of the impeller blade (82) of the turbine
wheel is enabled fluidly and a second position in which it is at
least essentially fluidly blocked, and a further adjusting device
(54) situated in a turbine wheel inlet area (110) for variably
adjusting the flow conditions in the turbine wheel inlet area (110)
upstream of the turbine wheel (74), the first adjusting device and
the second adjusting device (54, 56) being coupled to one another
and being operable by means of a single actuator.
2. The turbine (32) according to claim 1, wherein the adjusting
device (56) is situated, at least in parts, in a turbine wheel
outlet area (108) and is rotatable about the rotational axis (73)
of the turbine wheel (74).
3. The turbine (32) according, to claim 1, wherein the adjusting
devices (54, 56) are one of electrically, pneumatically,
hydraulically and mechanically coupled to one another.
4. The turbine (32) according to claim 1, wherein the second
adjusting device (54) is rotatable about the rotational axis (73)
of the turbine wheel (74) for variably adjusting the flow
conditions in the turbine wheel inlet area (110)
5. The turbine (32) according to claim 1, wherein the turbine wheel
blade (82) of the turbine wheel (74) has an outer contour (86) of
at least one length range (88), extending essentially parallel to
the rotational axis (73), and having as the leading edge (90), and
having a length range (94) extending essentially radially as the
trailing edge (96), whereby between the length range (88) extending
essentially parallel to the rotational axis (73) and the length
range (94) extending essentially radially, at least one further
length range (100) is provided forming a further trailing edge
(102), and defining an angle .alpha..sub.K with the rotational axis
(73), where .alpha..sub.K is in a range
20.degree.<.alpha..sub.K.ltoreq.90.degree..
6. The turbine (32) according to claim 5, wherein the further
trailing edge (102) may be selectively essentially fluidly enabled,
or essentially fluidly blocked, by means of the single adjusting
device (56).
7. The turbine (32) according to claim 1, wherein the adjusting
device (56) includes a first adjusting element (80) which is
rotationally fixed relative to the turbine housing (76), and at
least one second adjusting element (78) which is rotatable about
the rotational axis (73) relative to the first adjusting element
(80).
8. The turbine (32) according to claim 1, wherein the adjusting
device (56) is adjustable about the rotational axis (73) in an
adjustment range of 20 degrees.
Description
[0001] This is a Continuation-In-Part application of pending
international patent application PCT/EP2011/008095 filed Dec. 6,
2011 and claiming the priority of German patent application 10 2011
014 458.7 filed Mar. 19, 2011.
BACKGROUND OF THE INVENTION
[0002] The invention relates to a turbine for an exhaust gas
turbocharger including a turbine wheel with impeller blades having
leading and trailing edges and guiding the flow of exhaust gas
through the turbine.
[0003] It is known from the series production of internal
combustion engines to use exhaust gas turbochargers having a
turbine which is drivable by exhaust gas from the internal
combustion engine. The turbine may have at least one adjusting
device situated, for example, upstream of a turbine wheel of the
turbine in the direction of the flow of the exhaust gas, and by
means of which flow conditions, in particular upstream from the
turbine wheel, may be influenced. Thus, the turbine may be adapted
to a plurality of different operating points of the internal
combustion engine, so that the turbine, and thus the internal
combustion engine, may be operated in a particularly efficient
manner, i.e., with low fuel consumption and therefore low CO.sub.2
emissions. The adjusting device thus represents a variability which
allows an advantageous thermodynamic adaptation of the turbine to a
particular operating point. This variability results in options for
influencing the so-called reaction level of the turbine, which
represents a primary variable for efficiency-optimized
operation.
[0004] In addition, it is necessary to provide a certain throughput
range of the turbine in order to meet particularly large load and
speed range requirements of the internal combustion engine. To also
meet in particular requirements at low loads and/or speeds of the
internal combustion engines. It is possible, for example, to
provide for a high exhaust gas backup level of the turbine, which,
however, is accompanied by a low throughput parameter of the
turbine.
[0005] WO 2006/133838 A1 discloses an exhaust gas turbine in an
exhaust gas turbocharger, having a turbine wheel which is rotatably
mounted in a housing, to which exhaust gas, which is discharged by
the exhaust gas turbine via an outlet channel, is supplied via an
inlet duct The exhaust gas turbine has a turbine inlet cross
section which is formed in the transition area from the inlet duct
to the turbine wheel between two lateral duct walls, and in which a
guide vane structure and an axial slide which cooperates with the
guide vane structure and is adjustable in the axial direction is
situated, one of the guide walls of the turbine inlet passage being
displaceable and being formed by the axial slide. The guide vane
structure is fixedly mounted to the housing in the turbine inlet
cross section, so that the axial slide is situated at the side
facing the outlet channel, and the boundary wall of the turbine
inlet cross section, which is fixed to the housing and faces away
from the outlet channel, is axially flush with the turbine blades
of the turbine wheel.
[0006] The known turbines which have a corresponding adjusting
device have further potential for reducing their installation space
requirements, In addition, they have further potential for
providing more efficient operation.
[0007] It is the principal object of the present invention,
therefore to provide a turbine for an exhaust gas turbocharger
which requires less installation space and is more efficient in its
operation.
SUMMARY OF THE INVENTION
[0008] In a turbine for an exhaust gas turbocharger having a
turbine housing including a turbine wheel with blades, each having
a leading edge and a trailing edge, an adjusting device is provided
controlling the flow to the leading blade edges of the turbine
wheel and also a device for controlling the flow from the trailing
edges of the turbine wheel blades, both devices are coupled to one
another so as to be adjustable by a single actuator.
[0009] Such a turbine for an exhaust gas turbocharger includes a
turbine housing and a turbine wheel. The turbine wheel is
accommodated, at least in parts, in the turbine housing and is
rotatable about a rotational axis. The turbine wheel has at least
one impeller blade with a leading edge, and a trailing edge which
turbine wheel is driven by the exhaust gas flowing from the turbine
housing over the impeller blade via the leading edge and off from
the impeller blade via its trailing edge.
[0010] According to the invention, an adjusting device is provided
by means of which the trailing edge of the guide blade of the
turbine wheel may be fluidly enabled, at least in parts, in a first
position, and on the other hand may be at least essentially fluidly
blocked in at least one second position of the adjusting device In
other words, in a first position of the adjusting device in which
the trailing edge is fluidly enabled at least in parts, exhaust gas
may flow off a larger length range of the trailing edge than in the
second position of the adjusting device, in which the trailing edge
is at least essentially fluidly blocked.
[0011] The adjusting device of the turbine according to the
invention, which is, for example, a radial turbine allows the
turbine to be adapted as needed and in a particularly large
operating range to a plurality of different operating points of,
for example, a unit associated with the turbine, in particular an
internal combustion engine or a fuel cell, via the exhaust gas of
which the turbine is driven. This is accompanied by a more
efficient operation of the turbine and thus of the unit, so that
the unit may be operated with low energy consumption. If the unit
is an internal combustion engine, for example, this means
particularly low fuel consumption and low CO.sub.2 emissions of the
internal combustion engine.
[0012] In addition, the turbine according to the invention, in
which the adjusting device is situated for example downstream of
the turbine wheel, requires less installation space, which assists
in avoiding and solving packaging problems, in particular in a
space-critical area such as an engine compartment of a motor
vehicle.
[0013] Furthermore, due to the corresponding arrangement and
configuration of the adjusting device, the turbine according to the
invention may be designed with a particularly low weight, which
keeps the weight of the motor vehicle low. This results in more
efficient operation of the unit for driving the motor vehicle. In
addition, the flow conditions in the turbine wheel outlet area may
be set in a particularly advantageous manner by the adjusting
device, which is rotatable about the rotational axis, resulting in
more efficient operation of the turbine according to the
invention.
[0014] The adjusting device of the turbine according to the
invention provides a turbine wheel outlet variability which has
only a small number of parts and thus a low level of complexity,
which is accompanied by high functional reliability. This is
advantageous for the service life of the adjusting device, and
thus, of the overall turbine. In other words, the adjusting device
is in particular mechanically reliable and has only low costs.
[0015] By means of the adjusting device, a throughput of the
turbine is adjustable, in that the trailing edge is fluidly enabled
or, on the other hand fluidly blocked, at least in parts. Due to
the different positions of the adjusting device, a particularly
good throughput range of the turbine may thus be provided, so that
the turbine may be adapted to a plurality of different operating
points of the unit associated with it.
[0016] The turbine and the unit associated with it may thus be
operated more efficiently. In low speed and load ranges, a
relatively high back-up effect may be set by the adjusting device
with only a small throughput parameter, while in high speed and
load ranges of the internal combustion engine, a throughput
parameter which is higher in comparison may be set with only a
small accumulation effect. The turbine also requires less
installation space and has a very low weight, since the adjusting
device is situated in a manner which optimizes the installation
space.
[0017] In one advantageous embodiment of the invention, the
adjusting device is rotatable about the rotational axis of the
turbine wheel, and is situated at least partially in the area
around the turbine wheel outlet area. Flow conditions in the
turbine wheel outlet area are variably adjustable by means of the
adjusting device. This keeps the installation space requirements of
the turbine particularly low. In addition, the turbine thus has a
high level of robustness against mechanical and/or thermal
stresses, which is accompanied by very good functional reliability,
even over a long service life.
[0018] As a result of the enabling and, on the other hand, blocking
of the trailing edge, a contour of the turbine wheel may be varied,
and therefore a flow-off surface of the turbine wheel over which
exhaust gas which may flow off via the turbine wheel may be
variably adjusted and thus adapted to different operating points.
Due to this variation in the contour, by means of which the
flow-off surface is increased or decreased and trailing edges are
thus added or removed, the throughput parameter of the turbine may
be adjusted as needed, thus achieving particularly efficient
operation of the turbine. This results in an increase in efficiency
of the turbine, since the so-called reaction level of the turbine
may be influenced in this way.
[0019] On account of the adjustability of the throughput parameter,
the turbine thus has an optimized operating range due to adapting
the reaction level. In addition, this results in turbine efficiency
advantages and improved charge pressure build-up due to a
compressor, which is associated with, and drivable by, the turbine
for compressing air to be supplied to the unit, and also results in
corresponding low fuel consumption and reduced CO.sub.2
emissions.
[0020] In one advantageous embodiment of the invention, a further
adjusting device situated, at least in part, in the turbine wheel
inlet area is provided, by means of which flow conditions in the
turbine wheel inlet area upstream of the turbine wheel are variably
adjustable. A fully variable turbine is thus provided which may be
adapted to different operating points in a particularly
advantageous manner and in a particularly large operating range.
This results in a particularly efficient operation with low energy
consumption, in particular low fuel consumption, of the unit
associated with the turbine accompanied by low CO.sub.2
emissions.
[0021] For example, an effective flow cross section upstream of the
turbine wheel in the direction of flow of the exhaust gas through
the turbine is adjustable by means of the further adjusting device,
so that the accumulation effect as well as the throughput parameter
of the turbine according to the invention may also be variably
adjusted.
[0022] The further adjusting device includes, for example, a
blocking element, in particular a tongue, which is rotatable about
the rotational axis of the turbine wheel and by means of which the
effective flow cross section is adjustable. The blocking element is
connected to an adjusting ring, for example, which is rotatable
about the rotational axis of the turbine wheel and by means of
which the blocking element is movable, in particular rotatable, for
variably adjusting the effective flow cross section. The turbine
according to the invention is thus designed as a so-called tongue
diverler turbine which is adaptable to different operating points
in a particularly flexible manner and which has a low level of
complexity, which benefits the functional reliability and thus the
service life of the turbine.
[0023] In another advantageous embodiment of the invention, the
first adjusting device and the further adjusting device are coupled
to one another and are activatable, in particular movable, by means
of an actuator, in particular only one actuator, of the turbine
which is shared by the adjusting devices. The coupling of the
adjusting devices thus allows only one control element, for example
an actuator, in particular an electric motor, to be used for moving
the adjusting devices to adjust the effective flow cross section or
for enabling or blocking the trailing edge. It may be provided that
the adjusting devices are simultaneously movable due to the
coupling. Different displacement distances of the adjusting devices
may be provided by appropriate gear ratios and/or coupling
devices.
[0024] Combining the first adjusting device, and thus the
variability in the turbine wheel outlet area, with the further
adjusting device, and thus the variability in the turbine wheel
inlet area, allows full variability of a throughput characteristic
and reaction characteristic of the turbine according to the
invention, and thus a particularly good option for influencing the
efficiency curve. In the turbine according to the invention, this
full variability is provided using particularly simple and
inexpensive means in the form of the tongue diverter as the further
adjusting device, as well as the first adjusting device, so that
the turbine has high robustness and reliability.
[0025] The adjusting devices are, for example, electrically and/or
pneumatically and/or hydraulically and/or mechanically coupled to
one another. The electrical coupling has the advantage that a
response is made particularly quickly to changing operating points
of the unit associated with the turbine, and the adjusting devices
may be adjusted in a correspondingly rapid manner. In addition, a
particularly inexpensive coupling is thus provided.
[0026] The pneumatic and/or hydraulic coupling has the advantage
that particularly high actuating forces together with activating
forces that are particularly low in comparison may be provided in
order to adjust the effective flow cross section and/or to enable
or block the trailing edge, i.e., variably adjust the flow
conditions in the turbine wheel outlet area.
[0027] The mechanical coupling has the advantage of particularly
low costs as well as particularly high robustness and reliability,
which is conducive to the high functional reliability of the
turbine according to the invention, even at high stress levels and
over a long service life.
[0028] In another particularly advantageous embodiment of the
invention, the guide blade of the turbine wheel has an outer
contour having at least one length range, extending essentially
parallel to the rotational axis, as the leading edge, and having a
length range extending essentially radially as the trailing edge,
whereby, between the length range extending essentially parallel to
the rotational axis and the length range extending essentially
radially, at least one further length range is provided as a
further trailing edge, and which defines an angle .alpha..sub.K
with the rotational axis, where .alpha..sub.K is in a range
20.degree.<.alpha..sub.K<90.degree.. The at least essentially
radially extending trailing edge (length range) represents a
primary trailing edge which, for example, is at least practically
never fluidly blocked, and also not fluidly blockable by the first
adjusting device. The further trailing edge (length range)
represents a secondary trailing edge which may be fluidly enabled,
at least in parts, by means of the first adjusting device, and on
the other hand may be at least fluidly blocked. For this purpose,
the trailing edge is overlapped or covered, at least in parts, by
the first adjusting device, this overlap or cover being variably
adjustable in order to enable or block the trailing edge to a
greater or lesser extent.
[0029] The angle .alpha..sub.K or the corresponding angular range
represents a very important option for influencing the optimization
of the turbine wheel, since the through flow conditions as well as
in particular discharge flow conditions of the turbine wheel can be
influenced by the angle .alpha..sub.K. Accordingly, extremely
favorable through flow conditions are present in the mentioned
angular range, by means of which the turbine wheel allows
particularly efficient and efficiency-optimized operation of the
turbine, and thus, of the unit associated with the turbine.
[0030] It may be provided that the further trailing edge may be
fluidly enabled and on the other hand at least essentially fluidly
blocked by means of the first adjusting device, in that the
trailing edge is more or less overlapped or covered by means of the
first adjusting device, whereby, for example, only the further
trailing edge, and not also the first trailing edge, may be fluidly
enabled, or on the other hand, fluidly blocked. It may likewise be
provided that the first trailing edge may also be fluidly enabled,
or on the other hand, fluidly blocked by means of the first
adjusting device, the further trailing edge advantageously being
correspondingly adjustable, i.e., capable of being fluidly enabled,
or on the other hand, fluidly blocked, with respect to the first
trailing edge, predominantly by means of the first adjusting
device.
[0031] If the first adjusting device includes a first adjusting
element, in particular a first adjusting ring, which is
rotationally fixed relative to the turbine housing, and at least
one second adjusting element, in particular a second adjusting
ring, which is rotatable about the rotational axis relative to the
first adjusting element, an option which is particularly
uncomplicated, inexpensive, and reliable is provided for adjusting
the flow conditions in the turbine wheel outlet area, for example
by fluidly blocking or, on the other hand, enabling a flow past the
trailing edge.
[0032] The first adjusting device has for example an adjustment
range, in particular an adjustment angle range, with a first end
position and a second end position. In other words, the first
adjusting device is movable, in particular rotatable about the
rotational axis, in the adjustment range between the end positions.
It may be provided that the first adjusting device is movable into
the end positions, and also into at least one intermediate position
in the adjustment range between the end positions. The first
adjusting device is preferably continuously adjustable in the
adjustment range, so that a plurality of different positions of the
first adjusting device may be provided to be able to adapt the
turbine to different operating points in a particularly
advantageous manner. It is likewise possible to adjust the first
adjusting device in the adjustment range in a stepped manner, which
is accompanied by particularly low costs for the turbine.
[0033] If the first adjusting device is adjustable in an adjustment
range of 20.degree. about the rotational axis, i.e., the first
adjusting device has an adjustment angle of 20.degree., this is
advantageous since the turbine may be adapted to different
operating points in a particularly simple and cost-effective
manner, while at the same time the installation space requirements
of the turbine and its costs may be kept low.
[0034] Further advantages, features, and particulars of the
invention will become apparent from the following description of an
exemplary embodiment thereof with reference to the accompanying
drawings. The features and feature combinations mentioned above in
the description, as well as the features and feature combinations
mentioned below in the description of the figures and/or shown in
the figures are usable not only in the particular stated
combination, but also in other combinations or alone without
departing from the scope of the invention.
BRIEF DESCRIPTION OF THE DRAWINGS
[0035] FIG. 1 shows a schematic illustration of an internal
combustion engine having an exhaust gas turbocharger which includes
a turbine through which exhaust gas from the internal combustion
engine may flow, the turbine having an adjusting device, which is
rotatable about a rotational axis of a turbine wheel of the turbine
and situated, at least in part, in a turbine wheel outlet area
downstream from the turbine wheel, by means of which flow
conditions in particular in the turbine wheel outlet area are
variably adjustable;
[0036] FIG. 2 shows a section of a schematic longitudinal view of
the turbine according to FIG. 1; and
[0037] FIG. 3 shows a section of a schematic sectional view of the
turbine according to FIG. 2 along a sectional line A-B illustrated
in FIG. 2.
DESCRIPTION OF AN EXEMPLARY EMBODIMENT
[0038] FIG. 1 shows an internal combustion engine 10, designed as a
reciprocating piston machine, which may be a diesel engine,
gasoline engine, diesel-gasoline engine, or some other type of
internal combustion engine. The internal combustion engine 10 is
used, for example, to drive a motor vehicle, in particular a
passenger vehicle. To this end, the internal combustion engine 10
can be supplied with fuel which is delivered to at least one
combustion chamber, in particular a cylinder, of the internal
combustion engine 10. Air drawn in from the surroundings by the
internal combustion engine 10 is also supplied to the combustion
chamber of the internal combustion engine 10 as indicated by a
directional arrow 12.
[0039] The air initially flows through an air filter 16 situated in
an intake tract 14 of the internal combustion engine 10 for
cleaning the air. Following the air filter 16, the air is conducted
via appropriate intake piping to a compressor 20 of an exhaust gas
turbocharger 22 situated in the intake tract 14, as indicated by a
directional arrow 18 in FIG. 1.
[0040] The air is compressed by means of a compressor wheel of the
compressor 20, whereby the air is also heated. To increase the
degree of compression of the air, a charge air cooler 24 is
situated in the intake tract 14 downstream from the compressor 20;
the compressed air flows through the charge air cooler, which cools
the compressed air before it is ultimately supplied to the at least
one combustion chamber of the internal combustion engine 10 via the
intake piping. This is represented by a directional arrow 26.
[0041] Supplying the compressed air and the fuel to the at least
one combustion chamber results in a fuel-air mixture which ignites
by auto-ignition, for example, or which is ignited by means of an
ignition device and thus combusted. The combustion results in an
exhaust gas which flows out of the combustion chamber and into
exhaust piping of an exhaust tract 28 of the internal combustion
engine 10, as indicated by a directional arrow 30.
[0042] The exhaust gas is conducted via the exhaust piping in the
exhaust tract 28 to a turbine 32 of the exhaust gas turbocharger
22, the turbine being drivable by the exhaust gas. The turbine 32
includes a turbine housing 76 (FIG. 2) in which a turbine wheel 74
is accommodated so as to be rotatable about a rotational axis. The
turbine wheel 74 is connected to a shaft 4 of the exhaust gas
turbocharger 22 in a rotationally fixed manner, and may be acted
on, and thus driven, by the exhaust gas,
[0043] The compressor wheel of the compressor 20 is likewise
connected to the shaft 34 in a rotationally fixed manner, so that
the compressor wheel and thus the compressor 20 may be driven by
the turbine wheel 74, i.e., the turbine 32.
[0044] A branch point 36 is situated in the exhaust tract 30,
upstream from the turbine 32 in the direction of flow of the
exhaust gas through the exhaust tract 28, and is associated with an
exhaust gas recirculation device 38. At the branch point 36, an
exhaust gas recirculation line 40 of the exhaust gas recirculation
device 38 is fluidly connected to the exhaust piping of the exhaust
tract 28. On the other hand, the exhaust gas recirculation line 40
is fluidly connected to the intake piping of the intake tract 14 at
an inlet point 42. By means of the exhaust gas recirculation device
38, exhaust gas from the exhaust tract 28 is thus recirculatable to
the intake tract 14 and is introducible into the intake tract 14.
The air flowing through the intake tract 14 may thus be acted on by
exhaust gas from the internal combustion engine 10, so that
nitrogen oxides and particulate emissions from the internal
combustion engine 10 may be kept low.
[0045] For setting a quantity of exhaust gas to be recirculated as
needed, the exhaust gas recirculation device 38 includes an exhaust
gas recirculation valve 44 which is situated in the exhaust gas
recirculation line 40 and by means of which a flow cross section,
through which exhaust gas to be recirculated flows, is variably
adjustable. An exhaust gas recirculation cooler 46 is situated in
the exhaust gas recirculation line 40 between the inlet point 42
and the branch point 36, downstream from the exhaust gas
recirculation valve 44 in the direction of flow of the exhaust gas
through the exhaust gas recirculation line 40; the exhaust gas
recirculation cooler cools the exhaust gas to be recirculated.
Since the branch point 36 is situated upstream from the turbine 32,
high-pressure exhaust gas recirculation is provided by means of
which particularly large quantities of exhaust gas are
recirculated.
[0046] The internal combustion engine 10 includes a regulating
device 48 by means of which the internal combustion engine 10 and
the exhaust gas recirculation valve 44 can be regulated, as
indicated by arrows 50 and 52 in FIG. 1.
[0047] The turbine 32 has an adjusting device 54 situated, at least
in part, upstream from the turbine wheel 74 in the direction of
flow of the exhaust gas through the turbine 32. In addition, the
turbine 32 includes an adjusting device 56 situated, at least in
part, downstream from the turbine wheel 74 in the direction of flow
of the exhaust gas through the turbine 32. Flow conditions upstream
and downstream from the turbine wheel 74 are variably adjustable by
means of the adjusting devices 54 and 56, so that the turbine 32
may be adapted to a plurality of different operating points of the
internal combustion engine 10. In this way the turbine 32 is
operable in a particularly effective and efficiency-optimized
manner, which is accompanied by efficient operation of the internal
combustion engine 10. This results in particularly low fuel
consumption, and thus low CO.sub.2 emissions, of the internal
combustion engine 10.
[0048] As is apparent from FIG. 1, the adjusting devices 54 and 56
are coupled to one another by means of a coupling device 58, so
that the adjusting devices 54 and 56 are activatable by means of a
single actuator which is shared by the adjusting devices 54 and 56.
For this purpose, the coupling device 58 includes an actuating part
60 which is operated by an actuator, for example an electric motor.
The actuating part 60 is rotatable by means of the actuator, for
example, as indicated by an arrow 62, and/or is translationally
movable by means of the actuator, as indicated by a directional
arrow 64. A dashed line 66 indicates that the actuator is
controlled by the regulating device 48 so that it is able to adapt
the turbine 32, as needed, to an existing operating point of the
internal combustion engine 10.
[0049] After the exhaust gas has passed through the turbine 32 and
has been expanded in the turbine, it is further conducted via the
exhaust piping to an exhaust after-treatment device 68, situated in
the exhaust tract 28, as indicated by a directional arrow 70. The
exhaust after-treatment device 68 includes, for example, a
catalytic converter, in particular an oxidation catalytic
converter, and a particle filter by means of which the exhaust gas
is cleaned before it is discharged to the environment, as indicated
by a directional arrow 72.
[0050] The adjusting device 54 of the turbine 32 is, for example, a
so-called tongue diverter which has an adjusting ring that is
rotatable about a rotational axis 73. The rotational axis 73 is
also associated with the compressor wheel and the turbine wheel 74.
In other words, the compressor wheel, the turbine wheel 74, and the
shaft 34 rotate about the rotational axis 73 during operation of
the exhaust gas turbocharger 22.
[0051] Connected to the adjusting ring is at least one so-called
tongue which is rotatable about the rotational axis 73 via the
adjusting ring, and by means of which an effective flow cross
section upstream from the turbine wheel 74 is variably
adjustable.
[0052] The adjusting device 56 is designed, for example, as a
so-called rotary vane, which is explained in conjunction with FIG.
2 and FIG. 3. A wheel outlet cross section of the turbine wheel 74
is variably adjustable by means of the adjusting device 56.
[0053] As is apparent from FIG. 2, the adjusting device 56,
designed as a rotary vane, includes a first adjusting ring 78 which
is rotatable about the rotational axis 73 relative to the turbine
housing 76 and relative to the turbine wheel 74. In addition, the
adjusting device 56 includes an adjusting ring 80 which is fixed
relative to the housing 76.
[0054] The turbine wheel 74 has a plurality of impeller blades 82
which are uniformly distributed over the periphery of the turbine
wheel 74 in the peripheral direction of the turbine wheel 74, as
indicated by a directional arrow 84. The impeller blades 82 have an
outer contour 86 which has a first length range 88 extending at
least essentially parallel to the rotational axis 73. A leading
edge 90 of the impeller blade 82 is formed by the length range 88;
the exhaust gas may flow against the guide blade 32 for driving the
turbine wheel 74, For this purpose, the exhaust gas is supplied [to
the] turbine wheel 74 via an annular nozzle 92.
[0055] In addition, the outer contour 86 has a length range 94
which forms a trailing edge 96 of the impeller blade 82. The
exhaust gas may flow off from the impeller blades 82 via the
trailing edge 96. The length range 94, and thus the trailing edge
96, extends at least essentially in the radial direction of the
turbine wheel, as indicated by a directional arrow 98. The length
range 94, which extends at least essentially in the radial
direction, may, for example, define an angle with the rotational
axis 73 which is in a range from equal to or greater than, 80
degrees up to and including 100 degrees.
[0056] In the axial direction of the turbine wheel 74, as indicated
by a directional arrow 99, a length range 100 is provided between
the length ranges 88 and 94, and adjoins the length range 88 and is
adjoined by the length range 94 of the impeller blade 82. The
length range 100 forms a further trailing edge 102 of the impeller
blade 82, via which the exhaust gas may flow off the turbine wheel
74 or the impeller blade 82.
[0057] The length range 100, and thus the trailing edge 102,
defines, for example, an angle .alpha..sub.K with the rotational
axis 73 which, for example, is greater than 20 degrees and less
than or at least essentially equal to 90 degrees. Favorable
through-flow conditions of the turbine wheel 74 for the exhaust gas
are provided in this way.
[0058] The adjusting ring 78 includes cover elements 104 by means
of which the respective corresponding trailing edges 102 may be
fluidly overlapped, in particular completely, and in particular may
be completely enabled. For this purpose, the adjusting ring 78 may
be rotated about the rotational axis 73, according to a directional
arrow 106, into a respective end position. In addition, it is
possible to set the adjusting ring 78 in a plurality of
intermediate positions between the end positions in order to thus
enable the trailing edges 102 of the impeller blades 82, at least
in parts, to overlap or cover same in parts. Due to the different
positions of the adjusting ring 78, it is possible to set different
overflow gas quantities of the exhaust gas which flow off from the
turbine wheel 74 or the impeller blades 82 via the trailing edge
102. Variability in a turbine wheel outlet area 108 is thus
provided which is combined with variability in a turbine wheel
inlet area 110, which is specified by the adjusting device 54.
[0059] The turbine 32 is thus designed as a fully variable turbine
32 which may be adapted in a particularly flexible manner to
different operating points of the internal combustion engine 10. In
particular, the variability provided by the adjusting device 56 in
the turbine wheel outlet area 108 is characterized by only very
small installation space requirements, so that the overall turbine
32, and thus the overall exhaust gas turbocharger 22, requires only
a very small installation space, in particular in the axial
direction. In addition, as a result of the adjusting device 56
designed as a rotary vane, the complexity thereof as well as the
number of parts, the weight, and the costs may be kept low, which
contributes to a high level of functional reliability of the
turbine 32.
[0060] Figure illustrates one of the end positions of the adjusting
ring 78, in which the trailing edges 102 of the rotor blades 82 are
completely fluidly enabled. In this end position designed as an
open position, the turbine 32 has a maximum throughput
parameter.
[0061] If the adjusting ring 78 is displaced into the other of the
end positions, in which the trailing edges 102 are at least
essentially completely covered or overlapped, and thus at least
essentially completely fluidly blocked, a minimum throughput
parameter of the turbine 32 is provided. The turbine 32 then has a
particularly high accumulation effect, which is conducive to
efficient operation, in particular at low load and/or speed ranges
of the internal combustion engine 10. Providing the high throughput
parameter is beneficial for efficient operation of the turbine 32
at high load and/or speed ranges.
[0062] As is apparent in particular from FIG. 3, the cover elements
104 are spaced apart from one another in the peripheral direction
(directional arrow 84) and are at least essentially uniformly
distributed over the periphery of the turbine wheel 74. In this
way, a respective through flow channel 112 is formed between the
cover elements 104 in the peripheral direction, and exhaust gas may
flow through the through flow channel in positions of the adjusting
ring 78 in which flowing off of the exhaust gas from the impeller
blades 82 via the trailing edges 102 is made possible, at least in
parts
[0063] The through flow channels 102 have a diffuser-like design,
for example, so that they represent diffuser channels. The through
flow channels 112 designed as diffuser channels, for example, have
a trailing edge 114 in each case which has a very thin design.
[0064] Due to the covering or overlapping and enabling the trailing
edges 102, flow openings, so to speak, are enabled or fluidly
closed, at least in parts, so that the throughput parameter of the
turbine 32 may be influenced and the turbine 32 may be adapted to
operating points of the internal combustion engine 10 in a
particularly efficient manner. In other words, as a result of the
rotation of the adjusting ring 78, a contour of the turbine wheel
74 is variably adjusted and trailing edges 102 are added or
removed, so that flow-off surfaces are increased or decreased. As a
result, the turbine has a particularly high throughput range, so
that it may be efficiently be operated in low speed and/or load
ranges as well as in high speed and/or load ranges, and also in
intermediate speed and/or load ranges.
[0065] The adjusting device 56 has nine so-called blocking sectors
which are formed by the cover elements 104. The adjusting ring 78
is adjustable in an adjustment angle range of 20 degrees. This
means that the adjusting ring may be rotated overall by 20 degrees
relative to the adjusting ring 80, corresponding to the directional
arrow 84. This allows complete overlapping as well as complete
enabling of the trailing edges 102. In the position of complete
enabling, a maximum cross-sectional opening of 50% of the projected
ring surface area is achieved, as illustrated with reference to
FIG. 3. In this position, the turbine 32 has a maximum possible
flow cross section over the trailing edges 102.
[0066] As indicated in FIG. 2, the stationary adjusting ring 80 has
a relatively small thickness so that sector pockets 116 do not
constitute excessively large sources of loss for the flow of the
exhaust gas via the trailing edges 102.
[0067] In this regard, refinements, not illustrated in FIG. 2 and
FIG. 3, are possible in which the cover elements 104 or
corresponding blocking surfaces of the adjusting ring 78
increasingly submerge into the free sector pockets 116 due to an in
particular small axial motion during rotation of the adjusting ring
78, so that interfering edges for gap flows of the trailing edges
102 or of the outer contour 86 are at least essentially avoided in
the position in which the trailing edges 102 are completely
overlapped.
[0068] As is apparent from FIG. 2, the turbine 32, at least in
parts, includes no adjusting device such as the adjusting device 54
upstream from the turbine wheel 74 for variably adjusting the flow
conditions upstream from the turbine wheel 74. It is understood,
however, that an adjusting device such as the adjusting device 54
may be provided to be able to variably adjust the flow conditions
at least essentially upstream from the turbine wheel 74.
[0069] As is apparent from FIG. 1, the turbine 32 is associated
with the internal combustion engine 10. It is understood, however,
that the turbine 32 may also be associated with a fuel cell, for
example, the turbine 32 or the turbine wheel 74 then being drivable
by exhaust gas from the fuel cell, and the turbine 32 then being
adaptable to different operating points of the fuel cell in a
particularly efficient and flexible manner. In addition, the
turbine 32 may be associated with other types of units which emit
exhaust gas, and may be drivable by the exhaust gas from these
units.
* * * * *