U.S. patent application number 12/994531 was filed with the patent office on 2011-04-07 for drivetrain and method for providing a supply to a compressed air system.
This patent application is currently assigned to VOITH PATENT GMBH. Invention is credited to Markus Kley, Alexander Wunsch.
Application Number | 20110081257 12/994531 |
Document ID | / |
Family ID | 40910010 |
Filed Date | 2011-04-07 |
United States Patent
Application |
20110081257 |
Kind Code |
A1 |
Kley; Markus ; et
al. |
April 7, 2011 |
DRIVETRAIN AND METHOD FOR PROVIDING A SUPPLY TO A COMPRESSED AIR
SYSTEM
Abstract
The invention relates to a drivetrain, in particular motor
vehicle drivetrain, with a combustion engine having a drive output
shaft and which produces a hot exhaust-gas flow; with a
turbocompound system comprising: an exhaust-gas turbine which is
arranged in the exhaust-gas flow such that it can be impinged upon
by exhaust gas and which converts exhaust-gas energy into
propulsive energy, wherein the exhaust-gas turbine is
drive-connected, or can be switched so as to be drive-connected, to
the output shaft of the internal combustion engine and also drives
a turbocompressor or positive-displacement compressor by means of
which the internal combustion engine is charged on the fresh-air
side; with a compressed air system, comprising: an air compressor
which can be driven by means of the combustion engine or an
additional motor and which feeds compressed air into at least one
compressed-air circuit or a compressed-air line. The invention is
characterised by the fact that the air compressor can be charged by
means of the turbocompressor or positive-displacement compressor of
the turbocompound system, wherein air compressed by the
turbocompressor or positive-displacement compressor is supplied to
the air compressor on its intake side.
Inventors: |
Kley; Markus; (Ellwangen,
DE) ; Wunsch; Alexander; (Heidenheim, DE) |
Assignee: |
VOITH PATENT GMBH
Heidenheim
DE
|
Family ID: |
40910010 |
Appl. No.: |
12/994531 |
Filed: |
May 29, 2009 |
PCT Filed: |
May 29, 2009 |
PCT NO: |
PCT/EP2009/003845 |
371 Date: |
November 24, 2010 |
Current U.S.
Class: |
417/53 ;
417/364 |
Current CPC
Class: |
F02D 41/0007 20130101;
Y02T 10/12 20130101; Y02T 10/144 20130101; F02B 33/44 20130101;
F02D 23/00 20130101; F02B 21/00 20130101; F02B 37/04 20130101; F02M
23/065 20130101; Y02T 10/146 20130101 |
Class at
Publication: |
417/53 ;
417/364 |
International
Class: |
F04B 49/06 20060101
F04B049/06; F04B 35/00 20060101 F04B035/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 30, 2008 |
DE |
10 2008 026 023.1 |
Claims
1. Drivetrain, in particular motor vehicle drivetrain, having a
combustion engine having a drive shaft and generating a hot exhaust
gas stream; having a turbocompound system comprising: an exhaust
gas turbine, arranged in the exhaust gas stream to be impinged upon
by exhaust gas and converting exhaust energy into drive energy,
with the exhaust gas turbine drive-connected via a hydrodynamic
coupling to the drive shaft of the combustion engine or able to be
switched into one and also driving a turbocompressor or
displacement compressor by means of which the combustion engine is
supercharged on the fresh air side; having a compressed air system
comprising: an air compressor, which can be driven by means of a
combustion engine or an additional engine and which feeds its
compressed air into at least one compressed air circuit or into a
compressed air line; wherein the air compressor can be supercharged
by means of the turbocompressor or displacement compressor of the
turbocompound system, with the air compressed by the
turbocompressor or displacement compressor being supplied to the
air compressor on the intake side.
2. Drivetrain according to claim 1, wherein the air compressor is
developed as a piston-type compressor.
3. Drivetrain according to claim 1, wherein the compressed air
system is provided with a compressed air reservoir into which the
air compressor conveys compressed air and provision is made in
particular for a plurality of different compressed air circuits,
with at least one compressed air circuit being developed as a
compressed air brake circuit for vehicle brakes.
4. Drivetrain according to claim 1, wherein the air compressor is
drive-connected to the drive shaft of the combustion engine or can
be switched into one and can be motor driven to feed drive
output.
5. Drivetrain according to claim 1, wherein provision is made for a
connecting line for compressed air between the compressed air
system, in particular its compressed air reservoir, and the fresh
air side of the combustion engine, through which compressed air
from the compressed air system can be selectively conveyed to the
fresh air side of the combustion engine for supercharging.
6. Drivetrain according to claim 1, wherein in addition to the
turbocompound system provision is made for a turbocharger,
comprising a turbocharger turbine in the exhaust gas stream of the
combustion engine, in particular in the direction of flow of the
exhaust gas upstream from the exhaust turbine of the turbocompound
system, and a turbocharger compressor in a fresh air stream
conveyed to the combustion engine, in particular in the direction
of flow of fresh air downstream from the turbocompressor or the
displacement compressor of the turbocompound system, with the
turbocharger compressor being driven by the turbocharger turbine,
in particular arranged non-rotatably on a common shaft.
7. Drivetrain according to claim 6, wherein the air compressor can
be charged by means of the turbocompressor or the displacement
compressor of the turbocompound system and of the turbocharger
compressor, with an intercooler line, in particular that branches
off from the fresh air stream in the direction of flow after the
two compressors--turbocompressor/turbocharger compressor and
turbocharger compressor--and discharges on the intake side of the
air compressor.
8. Method for supplying a compressed air system, in particular a
motor vehicle compressed air system, involving the following steps:
an air compressor is driven by means of a combustion engine that
generates an exhaust gas stream or by means of a motor for which
additional provision is made; the air is compressed by means of an
air compressor and fed into at least one compressed air circuit
and/or one compressed air line; a turbocompressor or displacement
compressor is driven by means of an exhaust turbine arranged in the
exhaust gas stream, with said turbocompressor or displacement
compressor conveying fresh air to the combustion engine on the
fresh air side; compressed fresh air is supplied to the air
compressor on the intake side by means of the turbocompressor or
the displacement compressor; wherein in operational states where
the exhaust gas stream being fed into the exhaust turbine has a
comparatively low energy content, the exhaust turbine and/or the
turbocompressor or displacement compressor is driven.
9. Method according to claim 8, wherein the exhaust turbine and/or
turbocompressor or displacement compressor is driven by means of a
drive connection from a drive shaft of the combustion engine via a
hydrodynamic coupling to a shaft bearing the exhaust turbine and/or
the turbocompressor.
10. Drivetrain according to claim 2, wherein the compressed air
system is provided with a compressed air reservoir into which the
air compressor conveys compressed air and provision is made in
particular for a plurality of different compressed air circuits,
with at least one compressed air circuit being developed as a
compressed air brake circuit for vehicle brakes.
11. Drivetrain according to claim 2, wherein the air compressor is
drive-connected to the drive shaft of the combustion engine or can
be switched into one and can be motor driven to feed drive
output.
12. Drivetrain according to claim 3, wherein the air compressor is
drive-connected to the drive shaft of the combustion engine or can
be switched into one and can be motor driven to feed drive
output.
13. Drivetrain according to claim 2, wherein provision is made for
a connecting line for compressed air between the compressed air
system, in particular its compressed air reservoir, and the fresh
air side of the combustion engine, through which compressed air
from the compressed air system can be selectively conveyed to the
fresh air side of the combustion engine for supercharging.
14. Drivetrain according to claim 3, wherein provision is made for
a connecting line for compressed air between the compressed air
system, in particular its compressed air reservoir, and the fresh
air side of the combustion engine, through which compressed air
from the compressed air system can be selectively conveyed to the
fresh air side of the combustion engine for supercharging.
15. Drivetrain according to claim 4, wherein provision is made for
a connecting line for compressed air between the compressed air
system, in particular its compressed air reservoir, and the fresh
air side of the combustion engine, through which compressed air
from the compressed air system can be selectively conveyed to the
fresh air side of the combustion engine for supercharging.
16. Drivetrain according to claim 2, wherein in addition to the
turbocompound system provision is made for a turbocharger,
comprising a turbocharger turbine in the exhaust gas stream of the
combustion engine, in particular in the direction of flow of the
exhaust gas upstream from the exhaust turbine of the turbocompound
system, and a turbocharger compressor in a fresh air stream
conveyed to the combustion engine, in particular in the direction
of flow of fresh air downstream from the turbocompressor or the
displacement compressor of the turbocompound system, with the
turbocharger compressor being driven by the turbocharger turbine,
in particular arranged non-rotatably on a common shaft.
17. Drivetrain according to claim 3, wherein in addition to the
turbocompound system provision is made for a turbocharger,
comprising a turbocharger turbine in the exhaust gas stream of the
combustion engine, in particular in the direction of flow of the
exhaust gas upstream from the exhaust turbine of the turbocompound
system, and a turbocharger compressor in a fresh air stream
conveyed to the combustion engine, in particular in the direction
of flow of fresh air downstream from the turbocompressor or the
displacement compressor of the turbocompound system, with the
turbocharger compressor being driven by the turbocharger turbine,
in particular arranged non-rotatably on a common shaft.
18. Drivetrain according to claim 4, wherein in addition to the
turbocompound system provision is made for a turbocharger,
comprising a turbocharger turbine in the exhaust gas stream of the
combustion engine, in particular in the direction of flow of the
exhaust gas upstream from the exhaust turbine of the turbocompound
system, and a turbocharger compressor in a fresh air stream
conveyed to the combustion engine, in particular in the direction
of flow of fresh air downstream from the turbocompressor or the
displacement compressor of the turbocompound system, with the
turbocharger compressor being driven by the turbocharger turbine,
in particular arranged non-rotatably on a common shaft.
19. Drivetrain according to claim 5, wherein in addition to the
turbocompound system provision is made for a turbocharger,
comprising a turbocharger turbine in the exhaust gas stream of the
combustion engine, in particular in the direction of flow of the
exhaust gas upstream from the exhaust turbine of the turbocompound
system, and a turbocharger compressor in a fresh air stream
conveyed to the combustion engine, in particular in the direction
of flow of fresh air downstream from the turbocompressor or the
displacement compressor of the turbocompound system, with the
turbocharger compressor being driven by the turbocharger turbine,
in particular arranged non-rotatably on a common shaft.
Description
[0001] The present invention relates to a drivetrain, in particular
a motor vehicle drivetrain with a compressed air system and also a
method for supplying a compressed air system, in particular of a
motor vehicle compressed air system.
[0002] It is known for provision to be made for a compressed air
system in motor vehicles, particularly utility vehicles, referring
in the present case not only to road vehicles but also to rail
vehicles, which holds compressed air in readiness for the various
vehicle assemblies. As a rule, these assemblies are integrated in
compressed air circuits, which need to be re-filled with compressed
air from time to time due to the consumption of compressed air by
the assemblies and leakage. For instance, compressed air is
required for the brakes of a utility vehicle on the road or of a
rail vehicle on rail lines. Due to the high safety relevance of the
braking system it is necessary to have compressed air of sufficient
pressure and in sufficient quantity at one's disposal. The present
invention relates in particular to a vehicle with such a brake
compressed air circuit.
[0003] Patent application publication DE 34 35 732 A1 proposes
charging an air compressor in the form of a centrifugal compressor
powered by a combustion engine by means of a turbocompressor. To
this end, the turbocompressor, also known as a radial compressor or
precompressor, compresses fresh air that it supplies to the air
compressor via a cooler on the intake side. Thanks to this
pre-compression or supercharging, the air compressor itself can be
designed to be small as on the one hand it has to take in a smaller
volume of fresh air and on the other the pressure ratio between the
pressurised side and the intake side needs to be less. In the
aforementioned document the turbocompressor is powered by means of
an exhaust turbine arranged in the exhaust gas stream of the
internal combustion engine downstream from the turbine of an
exhaust turbocharger, with the exhaust turbocharger, as is already
known, serving to charge the combustion engine.
[0004] Further publications describing charged air compressors in
the form of displacement machines are DE 1 231 951 and DE 35 10 492
C2.
[0005] Although smaller air compressors should be able to be used
with the known drivetrains, in practice it has been shown that
these compressors are not able to provide sufficient compressed air
in certain operational states so that in contrast with the
aforementioned patent documents one must resort in practice to
comparatively large air compressors, which are actually designed
for systems without compressor precharging.
[0006] The aim of the present invention is to disclose a drivetrain
with a compressed air system accordingly and a method for supplying
a compressed air system with compressed air, which makes it
possible to supply sufficient compressed air in all prevailing
operating conditions, even with a comparatively small air
compressor.
[0007] The aim of the invention is fulfilled by a drivetrain and a
method according to the independent claims. The dependent claims
provide advantageous and particularly functional designs of
invention.
[0008] According to the invention, a turbocompound system and a
compressed air system of a drivetrain combine together in such a
way that the air compressor of the compressed air system is charged
by means of a turbocompressor or displacement compressor of the
turbocompound system. This means that the air compressor is
supplied with compressed air on its intake side by means of the
turbocompressor or displacement compressor, ensuring a sufficient
charge even in operational states with comparatively little exhaust
energy and/or with a comparatively small exhaust gas stream.
Conventional systems with charged compressors exhibit operational
states, namely at low speed and/or minimal combustion engine
output, in which only a low exhaust gas stream with low energy
impinges upon the exhaust turbine driving the turbocompressor. This
results in low precompression accordingly, making sufficient
charging by means of the turbocompressor impossible. According to
the invention, the drive output of the combustion motor can now be
used via the drive connection of the turbocompound system to drive
the turbocompressor or displacement compressor to precharge the air
compressor with the requisite power, even in operational states
with low exhaust flow and/or with low exhaust energy.
[0009] Specifically, the drivetrain according to the invention,
designed in particular as a motor vehicle drivetrain, has a
turbocompound system in addition to a combustion engine, said
system comprising an exhaust turbine to be impinged upon by exhaust
gas and arranged in the exhaust gas stream of the combustion engine
and a turbocompressor or displacement compressor driven by the
exhaust turbine. The exhaust turbine converts exhaust energy into
drive energy and can be drive-connected with the drive shaft of the
combustion engine or can be connected to one. In particular,
provision is made in the drive connection for a hydrodynamic
coupling, in particular a variable control hydrodynamic coupling.
In addition or alternatively, it is possible to design the
exhaust-gas power-recovery turbine to be governed with respect to
its power output.
[0010] The turbocompressor or displacement compressor serves to
charge the combustion engine, that means to compress fresh air that
is fed to the combustion engine for combustion together with fuel.
A displacement compressor that comes into consideration is for
instance the Roots supercharger. Other displacement compressors are
possible, with only rotating screw compressors or gear wheel pumps
being given as examples.
[0011] The drivetrain according to the invention is also provided
with a compressed air system comprising an air compressor that can
be actuated by means of the internal combustion engine and/or an
additional engine in order to feed compressed air into at least one
compressed air circuit. Provision can be made for example for a
compressed air brake circuit. In addition or as an alternative to
the compressed air circuit, provision can also be made for a simple
compressed air line into which the air compressor feeds compressed
air. One embodiment of such a compressed air line will be shown
with reference to the figure.
[0012] According to the invention, the air compressor can be
charged by means of a turbocompressor or displacement compressor of
the turbocompound system. This means that compressed air compressed
by the turbocompressor/displacement compressor can be fed to the
air compressor on its intake side such that the
turbocompressor/displacement compressor works as a supercharger for
the air compressor.
[0013] In particular, the air compressor is developed as a
piston-type compressor, for example as a single stage or two-stage
piston compressor.
[0014] As a rule, the compressed air system is provided with an
accumulator into which the air compressor conveys compressed air,
with a plurality of compressed air circuits being supplied
advantageously by means of the accumulator.
[0015] According to one embodiment, the air compressor can be
driven by a motor by means of the compressor converting the
compression energy from the compressed air fed into it into drive
energy, for example from the accumulator, one of the compressed air
circuits or the turbocompressor/displacement compressor. It is
particularly advantageous when the air compressor is arranged in a
drive connection with the drive shaft of the combustion engine or
such a connection can be switched to transmit propulsive power into
the drivetrain.
[0016] According to an advantageous embodiment, provision is made
for a connecting line between the compressed air system, in
particular its compressed air reservoir, and the fresh air side of
the combustion engine. The compressed air from the compressed air
system and/or the compressed air reservoir can be supplied to the
combustion engine on the fresh air side selectively through the
connecting line as an additional media flow.
[0017] For instance, a connecting line can discharge in the
direction of flow downstream from a turbocompressor of a
turbocharger, for which provision is made in addition to the
turbocompound, in particular after a downstream air cooler in the
fresh air flow on the fresh air side of the combustion engine.
[0018] In accordance with the method according to the invention for
supplying a compressed air system, in particular in a drivetrain
according to the invention, the following steps are executed:
[0019] an air compressor is powered by means of a combustion engine
generating an exhaust flow or by means of a motor for which
additional provision is made; [0020] air is compressed by means of
an air compressor and fed into at least one compressed air circuit
and/or one compressed air line; [0021] a turbocompressor or
displacement compressor, which compresses fresh air that is
supplied to the combustion engine on the fresh air side, is powered
by means of an exhaust turbine arranged in the exhaust gas stream;
[0022] furthermore, compressed fresh air is fed into the air
compressor on the intake side by means of the
turbocompressor/displacement compressor; wherein [0023] in
operational states where the exhaust gas stream being fed into the
exhaust turbine has a comparatively low energy content, the exhaust
turbine and/or the turbocompressor/displacement compressor is
driven by means of a combustion engine.
[0024] The invention shall be described in an exemplary manner on
the basis of one example embodiment and the figure.
[0025] FIG. 1 shows a schematic representation of a drivetrain with
a combustion engine 1, provided with a drive shaft 1.1. The
combustion engine 1 generates an exhaust gas stream 2, which is
first conveyed through the turbocharger turbine 10 of an exhaust
turbocharger 9 and then through the exhaust turbine 3 of a
turbocompound system 15.
[0026] The turbocharger turbine 10 drives a turbocharger compressor
11, for example as shown, via a common shaft bearing the
turbocharger turbine 10 and the turbocharger compressor 11 and/or
their runners. The turbocharger compressor 11 is arranged in a
fresh air stream 12 conveyed to the combustion engine 1. Said
turbocharger compressor compresses the fresh air stream using the
drive input from the turbocharger turbine 10, specifically in the
direction of flow of the fresh air stream 12 downstream from a
turbocompressor 4 of the turbocompound system driven by means of
the exhaust turbine 3. The exhaust turbine 3 and the
turbocompressor 4 and/or their runners can also be non-rotationally
connected to each other as shown, for example by means of a common
shaft.
[0027] After the fresh air stream 12 has been compressed by the
turbocompressor 4 and the turbocharger compressor 11, it is
conveyed through an intercooler 16 and finally supplied on the
fresh air side to the combustion engine 1. The intercooler 16 can
for instance be a component of the vehicle cooling system and be
arranged sequentially in terms of a heat exchanger 17 for the
vehicle cooling circuit 18, comprising a cooling water pump 19 with
respect to a cooling air stream 22 conveyed through the coolers 16
and 17. The output shaft 1.1 of the combustion engine drives an air
compressor 6 of a compressed air system 5. The air compressor 6,
shown in the present case as a two-stage compressor with two
cylinders, compresses the fresh air conveyed to it and feeds this
into a compressed air reservoir 7 of the compressed air system;
said air compressor could also be developed as a single stage
compressor with one cylinder as a result of the supercharging
according to the invention. In the present case, four compressed
air circuits K1-K4 are filled with compressed air from the
compressed air reservoir 7, with the upstream protection valve 23
preventing the pressure from falling in other compressed air
circuits if the pressure in one of the compressed air circuits
K1-K4 drops. In this way, the protection valve 23 separates the
compressed air circuits K1-K4 from each other in a pressure-tight
manner. One of the compressed air circuits is for example a
compressed air brake circuit. The compressed air reservoir 7 could
also be dispensed with or provision could be made in addition for
at least another compressed air reservoir. Provision could also be
made for a further compressed air circuit in place of the
compressed air reservoir 7.
[0028] According to a possible, but not compelling detail of the
embodiment represented, compressed air can be fed to the fresh air
side of the combustion motor 1 by means of the compressed air
reservoir 7, particularly in an advantageous manner, via a
connecting line 13, which for example has its outlet in the
direction of flow downstream from the turbocompressor 4 and the
turbocharger compressor 11 and in particular behind the intercooler
16. In the case of the embodiment shown, not only the connecting
line 13, but also the line 24 conducting the fresh air stream from
the intercooler 16 each have a control element, in particular an
electromechanically activated control flap 25, which prevents a
return flow of compressed air from the compressed air reservoir 7
toward the intercooler 16, making it possible for compressed air
from the compressed air reservoir 7 to be selectively supplied to
the fresh air side of the combustion engine 1. Of course, it is
also possible to arrange the outlet of the connecting line 13 at
another point in the fresh air stream 12, for instance ahead of the
intercooler 16, between the turbocompressor 4 and the turbocharger
compressor 11 or ahead of the turbocompressor 4. However, the
position indicated has proven to be advantageous as the compressed
air from the compressed air reservoir 7 does not generally need to
be cooled and supercharging is optimised by the embodiment
shown.
[0029] Of course, it would also be possible to run the connecting
line 13 between the compressed air system 5 or the compressed air
reservoir 7 and the fresh air side of the combustion engine 1 via
the protection valve 23 or connect it to one of the compressed air
circuits K1 to K4.
[0030] Provision is made for a branch 20 in the fresh air stream 12
downstream from the turbocharged turbine 11 and ahead of the
intercooler 16, with fresh air capable of being diverted from the
fresh air stream 12 via said branch and selectively guided to the
air compressor 6 for precharging the same via an intercooler line
8, in particular having a valve 21. For example, as shown, the
supercharged fresh air stream can be mixed with a compressed air
system fresh air stream 26. Alternatively, it is also possible to
dispense with the compressed air system fresh air stream 26 and to
compress all the fresh air supplied to the air compressor 6 by
means of the turbocompressor 4 and in particular additionally by
means of the turbocharger compressor 11.
[0031] Although the branch 20 shown in the present case is depicted
upstream of the intercooler 16 and downstream from the turbocharger
turbine 11, another position could be chosen, for example between
the turbocompressor 4 and the turbocharger compressor 11 or after
the intercooler 16 in the direction of flow. In the latter case,
relatively cooler air would be supplied to the air compressor 6,
something that can be advantageous with respect to the heat
generated by compression in the air compressor.
[0032] The drive output generated from the exhaust gas stream 2 by
means of the exhaust turbine 3 can be conveyed via the
turbocompound system 15 of the drive shaft 1.1 of the combustion
engine. Furthermore, if necessary due to unfavourable states in the
exhaust stream, the drive output of the combustion engine 1 can be
conveyed via the drive shaft 1.1 of the exhaust turbine 3 and
therefore to the turbocompressor 4 connected non-rotationally to
said drive shaft in order to drive the exhaust turbine 4. In this
way, sufficient drive output is available to charge the air
compressor 6 even during turbo lag operational states.
[0033] In the drive connection between the exhaust turbine 3 and
the output shaft 1.1 of the internal combustion engine 1, which is
developed in particular as a crankshaft, a hydrodynamic coupling 14
is arranged, which can be developed as a variable control coupling
as outlined. A variable control hydrodynamic coupling 14 includes
not only couplings with a volumetric efficiency control, but also
couplings, the circulatory flow of which can be interrupted by the
working fluid in the work space by means of an orifice plate in
order to reduce the output transmitted onto the turbine wheel from
the impeller.
[0034] Alternatively or additionally, it is also possible to
develop the exhaust turbine 3 and/or the turbocompressor 4 with a
variable control in order to control either the output transmitted
between the exhaust turbine 3 and the output shaft 1.1 of the
internal combustion engine 1 or to control the compressor output of
the turbocompressor 4. The turbine and/or the compressor can also
be controlled by opening and closing (partially or completely) a
bypass or a plurality of bypasses.
[0035] Not only is it possible to charge the air compressor 6 in
all operational states sufficiently with the drivetrain
represented, but also to convey an additional stream of compressed
air to the fresh air side of the combustion engine 1 from the
compressed air reservoir 7 or if required also from one of the
compressed air circuits K1-K4 in order to increase the output of
the combustion engine, particularly when the vehicle is moving off
from a standstill. Furthermore, although this is not shown,
provision can be made to convey compressed air from the compressed
air system 5, in particular from the compressed air reservoir 7, to
the exhaust gas stream 2 of the combustion engine in order to
modify the exhaust gas temperature, in particular to reduce it.
[0036] Also, the air compressor 6 can be actuated during vehicle
braking operations in order to exert a braking action on the drive
shaft 1.1 of the combustion engine 1 and at the same time to
temporarily store the generated energy in the compressed air
reservoir 7 in the form of compressed air. If required, the
compressed air can also be released into the environment through an
outlet valve when the compressed air reservoir 7 is full.
Alternatively or in addition, provision is also to be made in the
exhaust gas stream 2 for a so-called `waste gate`, from which
exhaust gas can be released before it is conveyed to the
turbocharger turbine 10 or the exhaust turbine 3.
* * * * *