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The present invention relates to a piston engine and, more particularly, to
a supercharged internal combustion piston engine which includes an exhaust
gas turbine, a supercharging compressor, a bypass line connecting a
charging or booster air line with an exhaust gas line, and a combustion
chamber disposed in a line between the charging or booster air line and
the exhaust gas turbine.
Arrangements have been proposed for cutting in and out the combustion
chamber to support the exhaust gas turbocharger in those operating states
in which the internal combustion engine itself does not produce sufficient
exhaust gases. In such proposed arrangements, expensive additional
assemblies are required to actuate the combustion chambers such as, for
example, electrically driven auxiliary blowers, compressed air reservoirs
whith shutoff, switching, and recharging devices, and/or auxiliary drives
for the exhaust gas turbocharger with connecting and disconnecting devices
to produce the required air throughput or throughflow through the
combustion chamber for ignition.
Under extreme starting conditions with, for example, low air temperatures
and/or low compression ratios in the internal combustion engine, it is
necessary to, for example, employ a precompression of the charging or
booster air and a preheating of such air in order to ensure a reliable
starting. While heating devices for heating aspirated air in the charging
or booster air line have been proposed for facilitating and/or permitting
starting of an internal combustion engine, installation of the heating
devices and/or combustion chambers in duplicate together with the
necessary control devices results in a considerable construction cost.
The aim underlying the present invention assentially resides in providing
an internal combustion engine arrangement which includes a combustion
chamber for achieving an intensive preheating of the charging air for the
internal combustion engine in addition to starting and supporting an
exhaust gas turbocharger.
According to one advantageous feature of the present invention, a
restricting and/or blocking means is arranged in an exhaust gas line
extending between a combustion chamber and an end of the exhaust gas line
with an exhaust gas return line, capable of being restricted and/or shut
off, branching off from the exhaust gas line at a position between the
combustion chamber and the restricting and/or blocking means with the
return line terminating in the charging air line.
In a piston-type internal combustion engine in which a combustion chamber
is disposed in a bypass line, according to another advantageous feature of
the present invention, the exhaust gas return line branches off from the
bypass line at a position between the combustion chamber and the exhaust
line with a valve means being provided for simultaneously or alternately
restricting and/or shutting off the return line and the passageway of the
bypass line between the point at which the return line branches off and
the exhaust gas line.
In accordance with further features of the present invention, the air is
aspirated into the piston engine through the bypass line, return line, and
through the combustion chamber when the engine is being started with the
combustion chamber being started by adding fuel and igniting the same to
heat the aspirated air from the piston engine with the piston engine then
being started by injecting fuel into the combustion spaces thereof.
By virtue of these last-mentioned features, a vacuum effect of the engine
can be used to start the combustion chamber without problems or any
special starting devices when starting up the internal combustion engine
and it is also possible to simultaneously achieve efficient heating of the
charging air for the engine.
According to the present invention, aspirated air from the internal
combustion engine may have additional air or exhaust gas added thereto
from the exhaust gas line by virtue of the provision of restricting and/or
blocking means in the exhaust gas line upstream of the exhaust gas
turbocharger with the restricting and/or blocking means being in the form
of control valves and/or adjustable vanes in the exhaust gas turbocharger.
By virtue of these measures, the air heated by the compressive efforts of
the internal combustion engine or the exhaust gas coming from the exhaust
line is mixed with the exhaust gases from the combustion chamber and fed
to the charging air.
When using an exhaust gas turbine which can be regulated by means of
adjustable vanes which can be used advantageously as a restricting or
blocking means in the exhaust gas line, the overall construction of the
engine of the present invention can be considerably simplified.
In accordance with yet another feature of the present invention,
immediately after starting or even during a starting phase, the exhaust
gases from the combustion chamber are available for accelerating the
exhaust gas turbocharger and/or for operating the exhaust gas turbocharger
with the piston engine under a partial load operation.
According to the present invention, the exhaust gases are supplied to the
combustion chamber in dependence upon the requirements of the engine and
exhaust gas turbocharger and as a function of operating parameters and the
operating state of the engine as well as the charging air for preheating
and exhaust gases from the piston engine to support the drive of the
exhaust gas turbocharger whereby operating with preheating of the charging
air and simulataneous support of the exhaust gas turbine is possible
during starting and under partial load operation of the engine so that a
transition can be made from preference for preheating chargin air to
increasing support for the exhaust gas turbine depending on thhe
requirements.
According to yet another advantageous feature of the present invention,
additional restricting and/or shutoff means are provided in the chargin
air line downstream of the point at which the bypass line branches off and
in the bypass line upstream of the combustion chamber with yet another
restriction and/or blocking means being arranged in the bypass line
leading from the combustion chamber to the branch-off position. The
restriction and/or blocking means are continuously variable and control
the throughflow by varying the cross-section of the respective lines
thereby providing for a continuous adjustment of the individual gas
streams in response to the changing operating parameters and operating
states of the internal combustion engine.
For optimum conditions, with varying operating states, in accordance with
the present invention, restricting and/or blocking means which can be
fixed or set permanently can be disposed in a valve arrangement to
determine the volume as well as the volume ratio of the individual gas
streams.
The restricting and/or blocking means according to the present invention
may advantageously be constructed as either individual valves and/or flat
valves or as a single multipath valve. With individual flat-type valves,,
there is provided a greater variety of possible means of regulation and
variation; whereas, the single multipath valve offers the advantages of
low cost and limited space requirements.
To provide additional support for heating the charging air, the exhaust
gases from the combustion chamber and the internal combustion engine can
be recycled to the charging air line according to the present invention by
providing a connecting line which includes a blocking and/or restricting
means with the connecting line extending from a point upstream of the
exhaust gas turbocharger to the chargin air line.
Th recycling of thhe exhaust gases can also be accomplished in accordance
with the present invention by providing a connecting line extending from
th exhaust gas line to the charging air line with the connecting line
including a restricting and/or blocking means and with a further
restricting and/or blocking means being disposed in the exhaust gas line
downstream of a point at which the connecting line branches from the
exhaust gas line.
A charging air cooler may be operatively connected to or disposed within
the charging air line according to the present invention in order to
achieve a high charging air input to the cylinders of the internal
combustion engine under a full load operation.
Advantageously, according to the present invention, the charging air is
heated during the starting process and under a partial load operation of
the internal combustion engine. For this purpose, the bypass line branches
off from the charging air line upstream of a charging air cooler with thhe
return line terminating in the charging air line downstream of the
charging air cooler. Restriction and/or blocking means are provided in the
bypass line for conrolling the throughflow of the air to the charging air
cooler.
An electrically driven auxiliary blower may be provided for supplying
auxiliary air to the combustion chamber to enhance the operation thereof.
In contrast to the conventional auxiliary blowers required to start the
combustion chamber, the auxiliary blower in accordance with the present
invention can be constructed with relatively small dimensions since the
blower supplies the combustion chamber with additional air only when
required in order to achieve a smooth combustion.
The internal combustion engine according to the present invention allows
for an advantageous use of a process for a zero-load and partial-load
operation to achieve good acceleration capability by feeding the total
volume of exhaust gases from the combustion chamber together with the
exhaust gases from the internal combustion engine to the exhaust gas
turbocharger thereby producing a high charging air pressure.
With low compression in the internal conbustion engine, at zero-load and
partial-load operation, to ensure sufficient ignition conditions,
according to the present invention, all of the exhaust gases from the
combustion chamber are added to the charging air by way of a return line
in order to preheat the charging air.
To facilitate the supply and control of the supply of the exhaust gases
from the combustion chamber and the internal combustion engine to the
charging air, a valve arragnement is provided for adding the exhaust gases
together and directing the exhaust gases to the charging air line.
According to the present invention, with a low compression ratio, in order
to ensure sufficient ignition conditions in the internal combustion
engine, all of the exhaust gases from the piston engine are fed to the
exhaust gas turbine to produce a high charging pressure and the charging
air is supplies to the internal combustion engine by bypassing a charging
air cooler.
Accordingly, it is an object of the present invention to provide an
internal combustion engine and method of operating the same which avoids
by simple means the disadvantages and drawbacks encountered in the prior
art.
Another object of the present invention resides in providing an internal
combustion engine and method of operating the same which facilitates
and/or improves and, under extreme conditions, makes possible the starting
and operation of the engine equipped with an exhaust gas turbocharger.
A further object of the present invention resides in providing an internal
combustion engine and method of operating the same which utilizes a
combustion chamber to achieve an intensive preheating of the charging air
while nevertheless reducing the overall construction costs of the engine.
Yet another object of the present invention resides in providing an
internal combustion engine and method of operating the same which
eliminates the previously required additional starting assemblies for
starting the combustion chamber.
A still further object of the present invention resides in providing an
internal combustion engine and method of operating the same which
functions reliably under all operating conditions.
These and other objects, features, and advantages of the present invention
will become more apparent from the following description when taken in
connection with the accompanying drawings which show, for the purposes of
illustration only, several embodiments of an internal combustion engine in
accordance with the present invention, and wherein:
FIG. 1 is a schematic representation of a first embodiment of a
supercharged internal combustion engine with a combustion chamber arranged
in an exhaust gas line;
FIG. 2 is a schematic representation of another embodiment of the internal
combustion engine in accordance with the present invention with a
combustion chamber disposed in a bypass line;
FIG. 3 is a schematic representation of a further embodiment of an internal
combustion engine in accordance with the present invention with a charging
air cooler and an additional exhaust gas feedback; and
FIG. 4 is a schematic representation of yet another embodiment of an
internal combustion engine in accordance with the present invention with
an exhaust gas feedback, guide vane control of an exhaust gas
turbocharger, and an additional auxiliary blower for the combustion
chamber.
Referring now to the drawings wherein like reference numerals are used
throughout the various views to designate like parts and, more
particularly, to FIG. 1, according to this figure, an internal combustion
piston engine 11 is connected by way of a charging air line 12 with a
compressor 13 and by an exhaust gas line 14 to an exhaust gas turbine 15.
A bypass line 16 is disposed between the charging air line 12 and the
exhaust gas line 14. A portion of the exhaust gas line 14 between the
piston engine 11 and the exhaust gas turbine 15 includes a combustion
chamber 17. A portion of the exhaust gas line 14 between the exhaust gas
turbine 15 and an end of the exhaust gas line 14 is provided with a
restricting and/or blocking means such as, for example, a single valve 18.
A return line 20 branches off from a portion of the exhaust gas line 14
between the exhaust gas turbine 15 and the valve 18 with the return line
20 terminating in the charging air line 12. A restricting and/or blockgin
valve 21 is provided for restricting and/or cutting off the flow of
exhaust gases through the return line 20.
In the embodiment of FIG. 1, the combustion chamber 17 is disposed in the
exhaust gas line 14 upstream of the exhaust gas turbine 15 and the valve
18 is disposed at the end of the exhaust gas line 14 downstream of the
exhaust gas turbine 15. As shown in dotted line, the return line 20 may
branch off the exhaust gas line 14 at a position between the exhaust gas
turbine 15 and the combustion chamber 17 upstream of the exhaust gas
turbine 15. However, as shown in dotted lines, in lieu of the valve 18, it
is possible to dispose a restriction and/or blocking means such as a valve
18' upstream of the exhaust gas turbine 15.
As shown in FIG. 2, the combustion chamber 17 is disposed in the bypass
line 16 extending between the chargin air line 12 and the exhaust gas line
14 with the return line 20 branching off from the bypass line 16 at a
point between the combustion chamber 17 and the exhaust gas line 14. The
valve 18 is disposed in the bypass line 16 between the branching place of
the return line 20 and the exhaust gas line 14. It is also possible to
branch off the return line 20 from the exhaust gas line 14 and to dispose
the valve 18 in the exhaust gas line 14 in the manner illustrated in FIG.
1.
As shown in FIG. 3, a restricting and/or blocking means such as a valve 24
is disposed in the exhaust gas line 14 upstream of the gas turbine 15
whereby exhaust gases from the internal combustion engine 11 and from the
combustion chamber 17 disposed in the return line 16 can be recycled back
to an exhaust gas return through a connecting line 25 which is controlled
by a valve 26 for restricting and/or blocking the connecting line 25. By
virtue of this arrangement, it is possible to preheat the aspirated air
especially during an idle operation and with the internal combustion
engine 11 operating at a low load level. Before the piston engine 11 is
started, the aspirated, compressed, and thereby additionally heated
charging air can be mixed with the exhaust gases from the combustion
chamber through the valve 18 and reaspirated. After the necessary air
temperature is reached in the internal combustion engine 11, fuel is then
injected into the combustion spaces of the engine in a conventional
manner.
A charging air cooler 31 is disposed in the charging air line 12 and is
bypassed by a bypass line 16 and return line 20 as the charging air is
heated up. An additional restricting and/or blocking means such as a valve
32 is disposed between the combustion chamber 17 and the branching off
point of the return line 20 for the bypass line 16.
A restricting and/or blocking means such as, for example, a valve 22 is
located upstream of the combustion chamber 17 for controlling the
throughflow through the combustion chamber 17 and an additional
restricting and/or blocking valve 23 is disposed in the charging air line
upstream of the charging air cooler 31.
By closing the control valve 18, the exhaust gas from the combustion
chamber 17 may be directed into the chargin air line or intake line of the
internal combustion engine 11. With the valves 18, 22, 26, 32, in an
opened position and the valve 24 in a closed position, the exhaust gas
from the combustion chamber 17 can be routed through the exhaust line 14
and connecting line 25 into the charging air line 12. When starting the
piston engine 11, the valve 23 is completely closed and the valve 22 is
completely opened. In lieu of the valve 24, the exhaust gas turbine 15
could be provided with adjustable guide vanes 27 (FIG. 4) to achieve the
same blocking and/or restricting functions.
As shown in FIG. 4, another connecting line 29 is provided in which is
arranged a restricting and/or blocking means such as, for example, a valve
28. A further restricting and/or blocking means, for example, a valve 30,
is provided in the exhaust gas line to slow down and/or control the flow
of the exhaust gases in the exhaust gas line 14. A bypass line 33,
provided with a restricting and/or blocking means such as a valve 34, is
provided for bypassing the charging air cooler 31. With the valve 23 in a
closed position and the valve 34 in a opened position, the bypass line 33
is cut in advantageously when the exhaust gases from the combustion
chamber are used to drive the exhaust gas turbine and the compressed
charging air is to be supplied to the piston engine without significant
cooling.
An auxiliary blower 37, driven by an electric motor 36, is provided at the
combustion chamber 17 and serves to improve the combustion process in the
combustion chamber 17 and to reduce the quantity of pollutants in the
exhaust gases. The auxiliary blower 37 supplies the combustion chamber 17
with additional air only when required in order to achieve a smooth
combustion.
In the FIG. 4 embodiment, the single valve 18 and valve 21 are integrated
into a valve arrangement 19 which functions to control the exhaust gas
flow in the same manner as the valves 18, 21. In this manner, ever when
the combustion chamber 17 is switched off, the exhaust gases can be
recycled through the return line 20. The valves 22, 23 are provided in the
bypass line 16 and charging air line 12 for respectively controlling the
flow through the combustion chamber 17 and the charging air cooler 31. As
with the embodiment of FIG. 3, the charging air cooler 31 in the charging
air line 12 is bypassed by the bypass line 16 and return line 20 when the
charging air is being heated up.
During a starting operation, the piston engine 11 creates a suction by way
of the compressor 13, chargin air line 12, bypass line 16, through
combustion chamber 17, by way of valves 18, 21 and/or valve arrangement
19, return line 20 and again through a section of the charging air line
12. At this time, the valve 18 and/or valve arrangement 19 is closed. In
the embodiments of FIGS. 1 and 2, by providing an appropriate diameter
ratio between the charging air line 12 on the one hand and the bypass line
16 and return line 20 on the other hand, indicated schematically by a
restriction 35 in the charging air line 12, most of the aspirated air is
passed through the combustion chamber 17.
When fuel is injected into the combustion chamber 17 and ignited in a known
manner, the ignition chamber 17 is started and the aspirated air
intensively preheated. In this fashion, unfavorable ignition conditions
such as, for example, a low compression ratio in the internal combustion
engine 11 and/or low outside air temperatures can be compensated so that
the injection of fuel into the internal combustion engine 11 then permits
the same to readily start.
As the piston engine 11 heats up further, the exhaust gases from the
combustion chamber 17 can be used to drive the exhaust gas turbine 15 in
the idle and partial load modes by closing valve 21 and opening valve 18
and/or by actuating valve arrangement 19. The continuously adjustable
restricting and/or blocking means allows this transition to be
accomplished continuously as a function of, for example, the charging air
pressure, aspirated air temperature and/or cooling water temperature, and
speed of the internal combustion engine 11 and/or exhaust gas turbine 15.
These meansures allow recharging pressure to be increased and the
rotational speed of the internal combustion engine 11 to be increased in a
much shorter period of time.
When the exhaust gas turbine 15 has reached its maximum speed with the
internal combustion engine 11 at a peak load, and the charging air has
reached its prescribed level, the combustion chamber 17 can be cut out.
Restricting and/or blocking valves 18, 21, and/or valve arrangement 19,
and restricting and/or blocking valves 22, 26, 28, and 34 are closed and
restricting and/or blocking valves 23, 24 and 30 are opened. Operation of
the piston engine 11 then proceeds in a conventional manner.
the restricting and/or blocking valves hereinabove can be controlled by
conventional electronic means which adjust the respective valves in
response to operating parameters and/or operating conditions of the
internal combustion engine 11. The valves may, for example, be flat-type
valves driven electrically as a function of the operating parameters and
suitable conventional means may be provided for controlling the ignition
and/or fuel metering for the internal combustion engine 11.
To start the engine 11, the engine aspirates air through the bypass line
16, return line 20, and through combustion chamber 17 with the combustion
chamber being started by adding fuel and igniting the same, thereby
heating the aspirated air from the engine 11. The engine 11 is then
started by injecting fuel into the combustion spaces thereof. Additional
air and/or exhaust gases from the exhaust gas line 14 may be added to the
aspirated air. In operating the engine 11, the exhaust gases are supplied
to the combustion chamber 17 in dependence upon the requirements of the
internal combustion engine 11 and the exhaust gas turbine 15 and as a
function of the operating parameters and/or operational state of the
engine 11, the preheating of the charging air, and the required amount of
exhaust gases from the internal combustion engine 11 necessary to support
the drive of the exhaust gas turbine 15.
For zero-load and partial-load operation of the engine 11, in order to
achieve good acceleration, the total volume of the exhaust gases from the
combustion chamber 17 together with the exhaust gases from the internal
combustion engine 11 are fed to the exhaust gas turbine 15.
If the engine has a low compression ratio, all of the exhaust gases from
the combustion chamber 17 are added to the charging air by way of the
return line 20 to preheat the charging air. Additionally, the exhaust
gases from th combustion chamber 17 together with the exhaust gases from
the internal combustion engine 11 may be fed to the exhaust gas turbine 15
with the charging air being supplied to the internal combustion engine 11
by bypassing the charging air cooler 31.
While we have shown and described several embodiments in accordance with
the present invention, it is understood that the same is not limited
thereto but is susceptible of numerous changes and modifications as known
to a person skilled in the art, and we therefore do not wish to be limited
to the details shown and described herein but intend to cover all such
changes and modifications as encompassed by the scope of the appended
claims.
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