Note: Descriptions are shown in the official language in which they were submitted.
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INTERNAL COMBUSTION ENGINE
The present invention concerns an internal combustion engine with an internal
combustion engine, and a genset comprising such an internal combustion engine.
Turbochargers have long been used to compress air, a fuel-air mixture or pure
fuel to a
higher pressure level before being fed to the combustion chambers of the
internal
combustion engine.
The surge line of the compressor of the turbocharger indicates that limit at
which, in the
event of exceeding it, an unstable operation, e.g. a flow reversal, occurs
through the
compressor.
The choke line of the compressor of the turbocharger indicates that limit at
which there
is no mass flow through the compressor in case of reaching the limit.
External and internal influences can lead to the position of the operating
point of the
compressor changing, and even to the surge line being reached or exceeded.
Aging of
the turbocharger can also lead to such a behaviour.
If the internal combustion engine is coupled with a generator to a genset, an
important
example of an external influence is a net fault in a power supply net
connected to the
genset. This can be for example a short circuit in at least one phase of the
power
supply net. This leads to an undervoltage and an overcurrent, which causes
strong and
rapid load changes with respect to the genset. Various national legal systems
stipulate
that the genset must remain connected to the energy supply net at least for a
certain
time in the event of a net Glow voltage ride through" - LVRT). Without
protective
measures, there may be disadvantageous effects on the genset.
Examples of internal influences are a damage at the turbocharger, misfiring
with
respect to at least one combustion chamber of the internal combustion engine,
etc.
The object of the invention is to provide an internal combustion engine, which
allows,
even in case of influences, which, in the state of the art, cause the surge
line of the
Date Recue/Date Received 2020-07-21
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compressor to be reached or exceeded, a stable operation of the turbocharger,
and a
genset with such an internal combustion engine.
As the closed loop or open loop control device is designed to regulate or
control the at
least one actuator in such a way that reaching the surge line is prevented by
the
operating point of the at least one compressor, stable operation of the
turbocharger is
possible even in case of negative external or internal influences.
The closed loop or open loop control device may, for example, be a central
closed loop
or open loop control device of the internal combustion engine.
Naturally, the possible positions of the operating point in the compressor map
are
limited by the maximum mechanical limits of the turbocharger.
It is preferably provided that the at least two operating parameters of the
turbocharger,
which are measured by the measuring device, are selected as follows:
- pressure ratio across the compressor
- volume flow or mass flow through the compressor
- rotation speed of the turbocharger
or parameters derived from these parameters.
It is preferably provided that at least one actuator is designed as a bypass
valve,
wastegate, variable valve train, throttle valve, inlet valve for air or a
mixture after the
compressor, as a variable turbine geometry, as an actuator for influencing the
point of
time of ignition, or for the shutdown of ignition devices for the combustion
chambers, or
as an actuator for influencing the quantity or point of time of injecting
liquid or gaseous
fuel into the combustion chambers.
It is preferably provided that the closed loop or open loop control device is
designed in
such a way that, if the operating point moves caused by external influences,
reaching
the surge line by the operating point is prevented.
Date Recue/Date Received 2021-09-23
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For this, a signalling device may be provided, which is connectable to a power
supply
net, and is designed to send a signal to the closed loop or open loop control
device
when a net fault of the power supply net is detected, whereby the closed loop
or open
loop control device is designed in such a way that, when such a signal is
received, an
activation of the at least one actuator is to be carried out as to prevent the
operating
point from reaching the surge line due to measures taken by the closed loop or
open
loop control device which serve to handle the net fault (in general: reduction
of the
output of the internal combustion engine, e.g. suspension of ignition or
setting the
ignition to "late").
This bears a number of advantages:
- The probability of reaching or exceeding the surge line during the LVRT is
reduced.
- The negative effects of a net fault during an LVRT regarding the
turbocharger are
reduced.
- Longer durations of the LVRT are possible.
- During the LVRT there is a lower power loss of the internal
combustion engine as
the functionality of the turbocharger is less impaired.
- Generators with a lower moment of inertia than previously possible can be
used.
It is preferably provided that the closed loop or open loop control device is
designed to
prevent the surge line being reached by the operating point if the operating
point
moves caused by an internal influence (e.g. damage at the turbocharger,
misfire with
respect to at least one combustion chamber of the internal combustion engine).
It is preferably provided that the closed loop or open loop control device is
designed to
prevent the surge line being reached by the operating point if the operating
point
moves caused by ageing of the compressor.
It is preferably provided that the closed loop or open loop control device is
designed to
cause the operating point to move along a predetermined path in the compressor
map
via the at least one actuator.
It may thereby be provided that the closed loop or open loop control device is
designed
to cause the operating point to move along a predetermined path in the
compressor
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map at least approximately parallel to the surge line via the at least one
actuator. The
closer the operating point remains to the surge line, the lower is the drop in
output of
the turbocharger, and thus of the internal combustion engine, because the
boost
pressure of the air, the fuel-air mixture or the pure fuel (depending on the
design of the
.. internal combustion engine, e.g. gas engine with mixture charging, gas
engine with port
injection, internal combustion engine with injection of liquid fuel, dual-fuel
internal
combustion engine) drops less strongly.
It may be provided that the closed loop or open loop control device is
designed to
cause the operating point to move along a predetermined path within a corridor
arranged in front of the surge line, preferably over a safety zone, via at
least one
actuator.
It is preferably provided that the closed loop or open loop control device is
designed to
calculate the activation of the at least one actuator in dependence on a
compressor
model. The way of calculation is taught, for example, in the following text
books:
- Hermann Hiereth, Peter Prenninger, Aufladung der
Verbrennungskraftmaschine ¨
Der Fahrzeugantrieb / chapter 5, 2003, published by Springer / Vienna
- Gunther P. Merker, Rudiger Teichmann, Grundlagen Verbrennungsmotoren
(Funktionsweise ¨ Simulation ¨ Messtechnik) / chapter 5 (Aufladesysteme), 7th,
completely revised edition, 2014, published by Springer/Vienna
- Gunther P. Merker, Christian Schwarz, Grundlagen Verbrennungsmotoren
(Simulation der Gemischbildung, Verbrennung, Schadstoffbildung und Aufladung)
/
chapter 8 (Aufladung von Verbrennungsmotoren) 4th, revised and updated edition
Vieweg + Teubner, GVVV Fachverlage GmbH, Wiesbaden 2009
It is preferably provided that the closed loop or open loop control device is
designed to
activate the at least one actuator depending on a pre-defined table. The table
can be
based on empirical values or created on a test stand.
The invention can preferably be used with a stationary internal combustion
engine, for
marine applications or mobile applications, such as so-called "non-road mobile
machinery" (NRMM), preferably in each case designed as a reciprocating piston
engine. The internal combustion engine can serve as a mechanical drive, e.g.
for
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operating compressor systems, or can be coupled with a generator to form a
genset for
generating electrical power. The internal combustion engine preferably has a
large
number of combustion chambers.
5 Embodiments of the invention are discussed using the figures. They show:
Fig. 1 a schematic illustration of an internal combustion engine according to
the
invention
Fig. 2 a compressor map of a turbocharger of an internal combustion engine
according to the invention.
Fig. 1 shows an internal combustion engine 10 with a plurality 15 of
combustion
chambers (if necessary connected with pre-chambers) shown only schematically,
with
not shown fuel supply facilities to the individual combustion chambers (e.g.
inlet valves
or active gas valves, port injection valves, injectors for liquid fuel, etc.),
a turbocharger,
which has a compressor 1 and an exhaust turbine 2, etc. An inlet tract 16 and
an outlet
tract 17 for air or a fuel-air mixture are shown.
Actuators for setting an operating point 4 of the turbochargers in the
compressor map
are shown examplatory, namely a throttle valve 12, a bypass valve 13, an inlet
valve
14, and a wastegate 3. Further actuators can be provided with respect to the
plurality
15 of combustion chambers (e.g. actuators for influencing the point of time of
ignition or
for shutdown of ignition devices for the combustion chambers, actuators for
influencing
the quantity or point of time of injecting liquid or gaseous fuel into the
combustion
chambers).
A measuring device 5 is provided for measuring at least two operating
parameters of
the turbocharger (here: pressure ratio across compressor 1, volume flow or
mass flow
through compressor 1 or rotational speed of the turbocharger) by means of
which a
position of an operating point 4 of the turbocharger in the compressor map is
determinable.
A closed loop or open loop control device 6 is connected to the measuring
device 5
(the connections are not shown), and designed to activate the actuators 3. The
closed
loop or open loop control device 6 is designed here as the central closed loop
or open
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loop control unit for the entire internal combustion engine 10, and can also
receive
measured data from the plurality 15 of combustion chambers (including the
assigned
components such as active gas valves, pressure in supply lines, etc.), as well
as issue
commands to the plurality 15 of combustion chambers or the assigned
components,
respectively.
For generating power, the internal combustion engine 10 is mechanically
connected
(via a shaft) to a generator 9 to form a genset, and is electrically connected
to a three-
phase power supply net 8. A signalling device 7 is provided, which is
connected or
connectable to the power supply net 8, and is designed to transmit a signal to
the
closed loop or open loop control device 6 upon detection of a net fault of the
power
supply net 8, whereby the closed loop or open loop control device 6 is
designed to
activate the at least one actuator upon receiving such a signal in such a way
that
reaching the surge limit by the operating point is prevented which could be
caused by
means of measures (see the explanations to Fig. 2), which serve the handling
of the
net fault, in particular with respect to the LVRT (in general: reduction of
the output of
the internal combustion engine, e.g. suspension of ignition or setting of
ignition to
"late").
Fig. 2 shows a compressor map of compressor 1 of the turbocharger (ordinate:
pressure ratio Tr over compressor 1, abscissa: temperature- and pressure-
compensated mass flow thred, whereby it can be seen that compressor 1 can be
operated stably in a stable operating range, which stable operating range is
limited by a
surge line P on the one hand, and by a choke line S on the other hand. The
dotted
lines show isoreduced rotational speed lines (i.e. rotational speeds of the
turbocharger
compensated by the input temperature). Other than shown, the ordinate can also
be
plotted with the temperature- and pressure-compensated volume flow.
The operating point 4 is plotted in a position which is given in stable
operation before a
net fault occurs. Not shown are minor movements of the operating point 4
around the
stable position, which can also occur during stable operation of the
turbocharger.
If the signalling device 7 detects a net fault of the power supply net 8, it
reports this to
the closed loop or open loop control device 6. The closed loop or open loop
control
device 6 is designed to regulate or control the actuators in such a way as to
prevent the
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surge line P being reached by the operating point 4 of compressor 1 of the at
least one
turbocharger despite the measures taken by the closed loop or open loop
control
device 6 for handling the net fault), and in particular with respect to the
LVRT.
If the operating point 4 reaches corridor B, the closed loop or open loop
control device
6, via the actuators, causes the operating point 4 to move along a specified
path within
corridor B, which over a safety area A is located in front of the surge line
P. Corridor B,
and thus the path, run at least approximately parallel to the surge line P.
When the net
fault has ceased, operating point 4 returns to its original position in the
compressor
map.
Safety zone A is selected in such a way that, on the one hand, a safe distance
from the
surge line P is maintained, and at the same time, on the other hand, not more
boost
pressure than necessary is reduced, so that sufficient boost pressure is
available again
.. after the net fault.
If the net fault lasts too long (e.g. if the so-called "clearing time" is
exceeded), the
connection between the genset and the power supply net 8 can be disconnected
by a
net switch 11.
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list of reference signs:
1 compressor of the turbocharger
2 exhaust turbine of the turbocharger
3 wastegate
4 operating point of the turbocharger in the compressor
5 measuring device for measuring at least two operating parameters of
the
turbocharger
to 6 closed loop or open loop control device
7 signalling device connected to the power supply net
8 power supply net
9 generator
internal combustion engine
11 power switch
12 throttle valve
13 bypass valve
14 inlet valve
15 plurality of combustion chambers
16 inlet tract
17 exhaust tract
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