Title: Internal combustion engine with an exhaust gas turbocharger and an exhaust gas recirculation device and method of operating same
Abstract: An internal combustion engine is provided which has an exhaust gas turbocharger and an exhaust gas recirculation device, and in which valve control times of intake valves and/or outlet valves of the individual cylinders of the internal combustion engine are different. Cylinders which supply an exhaust gas recirculation device have shorter valve overlap times or none at all in comparison with cylinders that do not supply the exhaust gas recirculation device. The internal combustion engine is preferably embodied as a diesel engine for truck applications.
Patent Number: 6,871,642 Issued on 03/29/2005 to Osterwald
| Inventors:
|
Osterwald; Henning (Leutenbach, DE)
|
| Assignee:
|
DaimlerChrysler AG (Stuttgart, DE)
|
| Appl. No.:
|
787255 |
| Filed:
|
February 27, 2004 |
| Current U.S. Class: |
123/568.11; 123/568.14; 123/568.21; 123/559.1 |
| Intern'l Class: |
F02D 047//08 |
| Field of Search: |
123/568.11,568.14,568.15,568.21,559.1,90.1
|
References Cited [Referenced By]
U.S. Patent Documents
| 4179892 | Dec., 1979 | Heydrich | 60/605.
|
| 4364345 | Dec., 1982 | Tsutsumi et al. | 123/198.
|
| 5562086 | Oct., 1996 | Asada et al. | 123/568.
|
| 5934263 | Aug., 1999 | Russ et al. | 123/698.
|
| Foreign Patent Documents |
| 28 55 687 | Aug., 1982 | DE.
| |
Primary Examiner: Mohanty; Bibhu
Attorney, Agent or Firm: Crowell & Moring LLP
Claims
What is claimed is:
1. Internal combustion engine having an exhaust gas turbocharger and an
exhaust gas recirculation device, whereby the internal combustion engine
has a plurality of cylinders and each cylinder of the internal combustion
engine has at least one intake valve and at least one outlet valve, and a
compressor of the exhaust gas turbocharger is assigned to an inlet and an
asymmetrical exhaust gas turbine of the exhaust gas turbocharger is
assigned to an outlet of the internal combustion engine, the compressor is
connected to the inlet via a charge air line, the exhaust gas turbine has
two intake ports with different flow cross sections which are separated
from one another by means of a partition and each inflow channel is
connected to the outlet through its own exhaust gas inlet line whereby
each exhaust gas inlet line is assigned a partial number of cylinders of
the internal combustion engine and an exhaust gas recirculation line leads
from the exhaust gas inlet line of the intake port having the smaller flow
cross section to the charge air line,
wherein a control unit is provided to control the valve control times of
the respective intake valves and/or the outlet valves of the individual
cylinders of the internal combustion engine to be different with the
cylinders supplying the exhaust gas recirculation device having shorter
valve overlap times or none at all in comparison with the cylinders not
supplying the exhaust gas recirculation device.
2. Internal combustion engine as claimed in claim 1, wherein the valve
control times of the intake valves of the cylinders which supply the
exhaust gas recirculation device are retarded.
3. Internal combustion engine as claimed in claim 1, wherein the
recirculated exhaust gas is divided differently among the individual
cylinders of the internal combustion engine, with a partial number of
cylinders of the internal combustion engine receiving the largest amount
or the total amount of the recirculated exhaust gas and the remaining
cylinders receiving the smallest amount or none at all of the recirculated
exhaust gas.
4. Internal combustion engine as claimed in claim 2, wherein the
recirculated exhaust gas is divided differently among the individual
cylinders of the internal combustion engine, with a partial number of
cylinders of the internal combustion engine receiving the largest amount
or the total amount of the recirculated exhaust gas and the remaining
cylinders receiving the smallest amount or none at all of the recirculated
exhaust gas.
5. Internal combustion engine as claimed in claim 3, wherein the cylinders
which do not supply the exhaust gas recirculation device receive the
largest amount of the recirculated exhaust gas or the total amount, and
the cylinders supplying the exhaust gas recirculation device receive the
smallest amount of recirculated exhaust gas or none at all.
6. Internal combustion engine as claimed in claim 4, wherein the cylinders
which do not supply the exhaust gas recirculation device receive the
largest amount of the recirculated exhaust gas or the total amount, and
the cylinders supplying the exhaust gas recirculation device receive the
smallest amount of recirculated exhaust gas or none at all.
7. Internal combustion engine as claimed in claim 1, wherein the internal
combustion engine is designed in the form of a series design having four
or six cylinders whereby a partial number of the cylinders that do not
supply the exhaust gas recirculation device amounts to at least half of
the total number of the cylinders of the internal combustion engine.
8. Internal combustion engine as claimed in claim 2, wherein the internal
combustion engine is designed in the form of a series design having four
or six cylinders whereby a partial number of the cylinders that do not
supply the exhaust gas recirculation device amounts to at least half of
the total number of the cylinders of the internal combustion engine.
9. Internal combustion engine as claimed in claim 3, wherein the internal
combustion engine is designed in the form of a series design having four
or six cylinders whereby a partial number of the cylinders that do not
supply the exhaust gas recirculation device amounts to at least half of
the total number of the cylinders of the internal combustion engine.
10. Internal combustion engine as claimed in claim 4, wherein the internal
combustion engine is designed in the form of a series design having four
or six cylinders whereby a partial number of the cylinders that do not
supply the exhaust gas recirculation device amounts to at least half of
the total number of the cylinders of the internal combustion engine.
11. Internal combustion engine as claimed in claim 5, wherein the internal
combustion engine is designed in the form of a series design having four
or six cylinders whereby a partial number of the cylinders that do not
supply the exhaust gas recirculation device amounts to at least half of
the total number of the cylinders of the internal combustion engine.
12. Internal combustion engine as claimed in claim 6, wherein the internal
combustion engine is designed in the form of a series design having four
or six cylinders whereby a partial number of the cylinders that do not
supply the exhaust gas recirculation device amounts to at least half of
the total number of the cylinders of the internal combustion engine.
13. Internal combustion engine as claimed in claim 1, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
14. Internal combustion engine as claimed in claim 2, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
15. Internal combustion engine as claimed in claim 3, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
16. Internal combustion engine as claimed in claim 4, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
17. Internal combustion engine as claimed in claim 5, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
18. Internal combustion engine as claimed in claim 6, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
19. Internal combustion engine as claimed in claim 7, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
20. Internal combustion engine as claimed in claim 8, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
21. Internal combustion engine as claimed in claim 9, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
22. Internal combustion engine as claimed in claim 10, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
23. Internal combustion engine as claimed in claim 11, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
24. Internal combustion engine as claimed in claim 12, wherein an exhaust
gas recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line.
25. A method of operating an internal combustion engine having an exhaust
gas turbocharger and an exhaust gas recirculation device, whereby the
internal combustion engine has a plurality of cylinders and each cylinder
of the internal combustion engine has at least one intake valve and at
least one outlet valve, and a compressor of the exhaust gas turbocharger
is assigned to an inlet and an asymmetrical exhaust gas turbine of the
exhaust gas turbocharger is assigned to an outlet of the internal
combustion engine, the compressor is connected to the inlet via a charge
air line, the exhaust gas turbine has two intake ports with different flow
cross sections which are separated from one another by means of a
partition and each inflow channel is connected to the outlet through its
own exhaust gas inlet line whereby each exhaust gas inlet line is assigned
a partial number of cylinders of the internal combustion engine and an
exhaust gas recirculation line leads from the exhaust gas inlet line of
the intake port having the smaller flow cross section to the charge air
line, said method comprising:
controlling the valve control times of the respective intake valves and/or
the outlet valves of the individual cylinders of the internal combustion
engine to be different with the cylinders supplying the exhaust gas
recirculation device having shorter valve overlap times or none at all in
comparison with the cylinders not supplying the exhaust gas recirculation
device.
26. A method according to claim 25, wherein the valve control times of the
intake valves of the cylinders which supply the exhaust gas recirculation
device are retarded.
27. A method according to claim 25, wherein the recirculated exhaust gas is
divided differently among the individual cylinders of the internal
combustion engine, with a partial number of cylinders of the internal
combustion engine receiving the largest amount or the total amount of the
recirculated exhaust gas and the remaining cylinders receiving the
smallest amount or none at all of the recirculated exhaust gas.
28. A method according to claim 27, wherein the cylinders which do not
supply the exhaust gas recirculation device receive the largest amount of
the recirculated exhaust gas or the total amount, and the cylinders
supplying the exhaust gas recirculation device receive the smallest amount
of recirculated exhaust gas or none at all.
29. A method according to claim 25, wherein the internal combustion engine
is designed in the form of a series design having four or six cylinders
whereby a partial number of the cylinders that do not supply the exhaust
gas recirculation device amounts to at least half of the total number of
the cylinders of the internal combustion engine.
30. A method according to claim 25, wherein an exhaust gas recirculation
valve in the form of a throttle valve is provided in the exhaust gas
recirculation line.
Description
BACKGROUND AND SUMMARY OF THE INVENTION
The invention relates to an internal combustion engine with an exhaust gas
turbocharger and an exhaust gas recirculation device. Preferred
embodiments of the invention relate to an internal combustion engine
having an exhaust gas turbocharger and an exhaust gas recirculation
device, whereby the internal combustion engine has a plurality of
cylinders and each cylinder of the internal combustion engine has at least
one intake valve and at least one outlet valve, and a compressor of the
exhaust gas turbocharger is assigned to an inlet and an asymmetrical
exhaust gas turbine of the exhaust gas turbocharger is assigned to an
outlet of the internal combustion engine, the compressor is connected to
the inlet via a charge air line, the exhaust gas turbine has two intake
ports with different flow cross sections which are separated from one
another by means of a partition and each inflow channel is connected to
the outlet through its own exhaust gas inlet line whereby each exhaust gas
inlet line is assigned a partial number of cylinders of the internal
combustion engine and an exhaust gas recirculation line leads from the
exhaust gas inlet line of the intake port having the smaller flow cross
section to the charge air line.
There are known supercharged internal combustion engines, in particular
diesel engines, which are equipped with an exhaust gas recirculation
device to improve exhaust performance. The exhaust gas recirculation by
means of the exhaust gas recirculation device serves in particular to
reduce NOx emissions. These internal combustion engines have an exhaust
gas turbocharger whose compressor is assigned to an inlet and whose
exhaust gas turbine is assigned to an outlet of the internal combustion
engine. The exhaust gas turbine and the outlet are connected by at least
one exhaust gas inlet line from which an exhaust gas recirculation line of
the exhaust gas recirculation device branches off. The exhaust gas
recirculation line opens into a charge air line which connects the
compressor to the inlet. An exhaust gas recirculation valve with which the
exhaust gas recirculation is controllable is provided in the exhaust gas
recirculation line.
U.S. Pat. No. 4,179,892 (corresponding German Patent DE 28 5 687 C2)
describes an internal combustion engine in which the exhaust gas turbine
has two separate intake ports (referred to as scroll channels in this
publication) and an exhaust gas inlet line (referred to in the publication
as an exhaust gas line) is assigned to each intake port. The exhaust gas
inlet lines connect the intake ports to the outlet of the internal
combustion engine. Each exhaust gas inlet line is connected separately
from the others to a partial number of cylinders of the internal
combustion engine. The intake ports have different flow cross sections.
The exhaust gas recirculation line branches off from the exhaust gas inlet
line which is assigned to the intake port having the smaller flow cross
section. The flow cross section of the intake port and/or the exhaust gas
inlet line is advantageously selected to be so small that there is a
negative purging gradient so that at least a portion of the exhaust flows
through the exhaust gas recirculation line into the charge air line. The
recirculated exhaust is distributed uniformly among the cylinders.
The negative purging gradient results in an inferior purging and/or an
increase in an internal exhaust gas recirculation of the cylinders which
supply the exhaust gas recirculation device.
It has been found that with a uniform distribution of the recirculated
exhaust gas to all the cylinders of the internal combustion engine, the
exhaust gases of the cylinders supplying the exhaust gas recirculation
device have a lower NOx concentration and a higher CO concentration in the
exhaust than do the cylinders which do not supply the exhaust gas
recirculation device. The higher CO concentration is an indicator of a low
.lambda. value, which is reflected in an increased output of carbon black
and/or particles in diesel engine combustion.
An object of the present invention is to make available an internal
combustion engine of the type referred to above so that its emissions are
distributed uniformly over all the cylinders of the internal combustion
engine.
This object is achieved according to certain preferred embodiments of the
invention by providing an internal combustion engine having an exhaust gas
turbocharger and an exhaust gas recirculation device, whereby the internal
combustion engine has a plurality of cylinders and each cylinder of the
internal combustion engine has at least one intake valve and at least one
outlet valve, and a compressor of the exhaust gas turbocharger is assigned
to an inlet and an asymmetrical exhaust gas turbine of the exhaust gas
turbocharger is assigned to an outlet of the internal combustion engine,
the compressor is connected to the inlet via a charge air line, the
exhaust gas turbine has two intake ports with different flow cross
sections which are separated from one another by means of a partition and
each inflow channel is connected to the outlet through its own exhaust gas
inlet line whereby each exhaust gas inlet line is assigned a partial
number of cylinders of the internal combustion engine and an exhaust gas
recirculation line leads from the exhaust gas inlet line of the intake
port having the smaller flow cross section to the charge air line, wherein
a control unit is provided to control the valve control times of the
intake valves and/or the outlet valves of the individual cylinders of the
internal combustion engine differently whereby the cylinders supplying the
exhaust gas recirculation device have shorter valve overlap times or none
at all in comparison with the cylinders not supplying the exhaust gas
recirculation device.
Preferred embodiments of the inventive internal combustion engine are
characterized by the valve control times of the intake valves and/or the
outlet valves of the individual cylinders of the internal combustion
engine which are provided differently, whereby the cylinders supplying the
exhaust gas recirculation device have shorter valve overlap times or none
at all in comparison with the cylinders that do not supply the exhaust gas
recirculation device. The internal combustion engine has an exhaust gas
turbocharger having an asymmetrical exhaust gas turbine. The asymmetrical
exhaust gas turbine has two intake ports which have a different flow cross
section. One flow cross section is selected to be so small that it results
in a negative flow gradient on the partial number of cylinders that are
connected to the intake port having the smaller flow cross section. The
exhaust gas of this cylinder can thereby be recirculated via an exhaust
gas recirculation device. The valve control times of the intake valves and
the outlet valves usually have a valve overlap in internal combustion
engines, i.e., the inlet opens before the outlet closes. Due to the valve
overlap, there is internal exhaust gas recirculation in particular when
there is a negative purging gradient. When the inlet is opened, the
pressure in the cylinder space drops below the exhaust gas pressure and
exhaust remains in the cylinder space or flows out of the outlet and back
(internal exhaust gas recirculation). The degree of internal exhaust gas
recirculation can be influenced with the design of the valve overlap times
and can be shortened to advantage. This makes it possible to keep the NOx
emissions at a required level while at the same time lowering CO emissions
which is reflected in reduced carbon black and particulate emissions.
Advantageous refinements of and improvements on the above discussed
preferred embodiment of an internal combustion engine are described herein
and in the claims.
In certain preferred embodiments of this invention, the valve control times
of the intake valves of the cylinders supplying the exhaust gas
recirculation device are retarded. Advantageously the retarding of the
valve control times is performed with a uniform valve lift diagram by five
degrees of crank angle in the retarded direction.
In certain other preferred embodiments of this invention, the recirculated
exhaust is divided in different ratios among the individual cylinders of
the internal combustion engine, with a partial number of the cylinders of
the internal combustion engine receiving all or most of the recirculated
exhaust gas while the remaining cylinders receive the smallest amount of
the recirculated exhaust gas or none at all. The ratio of the charge air
required for combustion and the exhaust gas recirculated from the internal
exhaust gas recirculation by means of the exhaust gas recirculation device
can be balanced out among the cylinders of the internal combustion engine.
In certain other preferred embodiments of this invention, the cylinders
that do not supply the exhaust gas recirculation device receive the
largest amount or all of the recirculated exhaust and the cylinders
supplying the exhaust gas recirculation device receive the smallest amount
or none of the recirculated exhaust. In an expedient embodiment of this
division, the cylinders not supplying the exhaust gas recirculation device
receive a 70% portion of the exhaust recirculated via the exhaust gas
recirculation device. The cylinders supplying the exhaust gas
recirculation device receive a 30% share accordingly.
In certain other preferred embodiments of this invention the internal
combustion engine is designed in the form of an in-line design with four
or six cylinders, whereby the partial number of cylinders not supplying
the exhaust gas recirculation device amounts to at least half of the
cylinders of the internal combustion engine. Due to the negative purging
gradient on the cylinders supplying the exhaust gas recirculation device,
the efficiency drops because of the inferior purging of the cylinders. The
loss of efficiency can be compensated by optimized charge alternation of
the cylinders that do not supply the exhaust gas recirculation device. In
order to avoid a negative effect on the overall efficiency of the internal
combustion engine, the partial number of cylinders supplying the exhaust
gas recirculation device is limited to at most half of the cylinders of
the internal combustion engine.
In certain other preferred embodiments of this invention, an exhaust gas
recirculation valve in the form of a throttle valve is provided in the
exhaust gas recirculation line. The exhaust gas recirculation valve is
controllable by means of a signal line by a control unit of the internal
combustion engine. Thus the exhaust gas recirculation is controllable by
means of the exhaust gas recirculation device and is adaptable to an
engine characteristics map of the internal combustion engine.
Additional features and combinations of features are derived from the
description and the drawing. A concrete exemplary embodiment of this
invention is shown in simplified form in a drawing and explained in
greater detail in the following description.
Other objects, advantages and novel features of the present invention will
become apparent from the following detailed description of the invention
when considered in conjunction with the accompanying drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a schematically simplified diagram of the inventive internal
combustion engine according to a single exemplary embodiment; and
FIG. 2 shows a simplified diagram of the valve control times of the
inventive internal combustion engine.
DETAILED DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a first embodiment of an inventive internal combustion engine
1. The internal combustion engine 1 is preferably designed as a diesel
engine in series design and has an exhaust gas turbocharger 2 and an
exhaust gas recirculation device 3. The exhaust gas turbocharger 2 has a
compressor 4 and an asymmetrical exhaust gas turbine 5. The compressor 4
and the exhaust gas turbine 5 are connected to one another rotationally by
a shaft 6. The compressor 4 is assigned to an inlet 7 and the asymmetrical
exhaust gas turbine 5 is assigned to an outlet 8 of the internal
combustion engine 1.
The compressor 4 is connected to the inlet 7 via a charge air line 9. A
charge air cooler 10 is provided in the charge air line 9. The inlet 7 has
an air charging distribution tube 11 from which at least one air charging
channel 12, 13, 14, 15, 16, 17 leads to a cylinder 18, 19, 20, 21, 22, 23
of the internal combustion engine 1. The cylinders of the internal
combustion engine 1 each have at least one intake valve (not shown) and an
outlet valve (not shown). The charge air line 9 opens into the charge air
distribution tube 11.
The asymmetrical exhaust gas turbine 5 has two intake ports 24, 25 which
are separated from one another by a partition 26 and have different flow
cross sections. Each inflow channel 24, 25 is connected to a separate
exhaust gas inlet line 27, 28 of the outlet 8 of the internal combustion
engine 1. It is also contemplated that the exhaust gas inlet lines 27, 28
may have different cross sections according to the flow cross sections of
the inflow channels 24, 25. Each exhaust gas inlet line 27, 28 is assigned
a partial number of cylinders of the internal combustion engine 1. In the
exemplary embodiment, the exhaust gas inlet line 27 is assigned the
cylinders 18, 19, 20 and the exhaust gas inlet line 28 is assigned the
cylinders 21, 22, 23. A different allocation of the cylinders to the
exhaust gas inlet lines 27, 28 is also contemplated. In addition, the
internal combustion engine 1 may also have a different number of cylinders
and a different design.
An exhaust gas recirculation line 29 of the exhaust gas recirculation
device 3 branches off from the exhaust gas inlet line 27. The exhaust gas
recirculation line 29 opens into the charge air line 9 just before the
mouth of the charge air line 9 into the charge air distribution tube 11.
In addition to the exhaust gas recirculation line 9, the exhaust gas
recirculation device 3 includes an exhaust gas recirculation cooler 30 and
exhaust gas recirculation valve 31. The exhaust gas recirculation valve 31
is designed as a throttle valve and is operable with an electric or
pneumatic actuating element (not shown). The actuating element is
triggerable via a signal line 32 by a controller 33 of the internal
combustion engine 1. Thus an exhaust gas recirculation is controllable by
means of the exhaust gas recirculation device 3 and is adaptable to an
engine characteristics map of the internal combustion engine 1. The
exhaust gas recirculation valve 31 is preferably provided close to the
opening of the exhaust gas recirculation line 29 into the charge air line
9. Mounting the exhaust gas recirculation valve 31 in the exhaust gas
recirculation line 29 near the mouth into the exhaust gas inlet line 27 or
directly on the exhaust gas inlet line 27 is also contemplated.
The compressor 4 is driven by the asymmetrical gas turbine 5. The
compressor 4 supplies the charge air required for combustion. The
compressor 4 draws in the air required for combustion through an intake
line 34 from the atmosphere. The compressed charge air flows through the
charge air line 9 and the charge air cooler 10 into the charge air
distribution tube 11 of the inlet 7 and through the charge air channels
12, 13, 14, 15, 16, 17 and continues into the cylinders 18, 19, 20, 21,
22, 23 of the internal combustion engine 1. The exhaust gases of the
cylinders 18, 19, 20, 21, 22, 23 flow into the exhaust gas inlet lines 27,
28 of the outlet 8 into the intake ports 24, 25 of the exhaust gas turbine
5. The exhaust gas drives the exhaust gas turbine 5 and flows through an
exhaust gas system 35, represented by an arrow in FIG. 1, into the
atmosphere.
Due to the different flow cross sections of the intake ports 24, 25, the
exhaust gas pressures in the exhaust gas inlet lines 27, 28 are different.
The partition 26 between the intake ports 24, 25 prevents an equalization
of pressure between the intake ports 24, 25. The smaller flow cross
section of the intake port 24 generates a negative purging gradient on the
cylinders 18, 19, 20. Due to the negative purging gradient, the exhaust
gas pressure is higher than the charge air pressure so that at least a
portion of the exhaust gas flows into the charge air line 9 through the
exhaust gas recirculation line 29 when the exhaust gas recirculation valve
31 of the exhaust gas recirculation device 3 is opened. The recirculated
exhaust is cooled in the exhaust gas recirculation cooler 30 and thus
serves to reduce NOx emissions in particular. The larger flow cross
section of the intake port 25 results in a positive purging gradient on
the cylinders 21, 22, 23, resulting in the highest possible efficiency.
Due to the negative purging gradient, the purging of the cylinders 18, 19,
20 that supply the exhaust gas recirculation line changes in such a way
that more exhaust remains in the cylinders 18, 19, 20 which supply the
exhaust gas recirculation device 3 and/or more gas flows back through the
outlet 8 than in the cylinders 21, 22, 23 that do not supply the exhaust
gas recirculation device 3 (internal exhaust gas recirculation).
The charge air line 9 does not open centrally into the charge air
distribution tube 11 but instead opens eccentrically, so that at the
cylinders 21, 22, 23, the charge air and the entrained recirculated
exhaust flow into the charge air channels 15, 16, 17 on entering the
charge air distribution tube 11. Thus the cylinders 21, 22, 23 which do
not supply the exhaust gas recirculation device 3 receive the greater
and/or total amount of the exhaust gas recirculated by means of the
exhaust gas recirculation device 3. Therefore the ratio of the internal
exhaust gas recirculation and the exhaust gas recirculated by means of the
exhaust gas recirculation device 3 to the charge air required for
combustion in the cylinders 18, 19, 20, 21, 22, 23 of the internal
combustion engine 1 is controllable. This advantageously results in a
uniform distribution of emissions over all the cylinders of the internal
combustion engine 1.
Another contemplated design of the inventive internal combustion engine 1
is one in which the cylinders 18, 19, 20 and the cylinders 21, 22, 23 each
have separate air charging distribution tubes 11 and the exhaust gas
recirculation line 29 opens only into the charge air distribution tube 11
that is assigned to the cylinders 21, 22, 23 that do not supply the
exhaust gas recirculation device 3.
Another contemplated design of the internal combustion engine 1 according
to this invention is one in which the exhaust gas recirculated by means of
the exhaust gas recirculation device 3 is sent directly to the air
charging channels 15, 16, 17.
An embodiment of the inventive internal combustion engine 1 in which the
exhaust gas recirculation valve 31 is designed as a switched throttle
valve is also conceivable. This makes it possible, for example, to add the
recirculated exhaust gas to the charge air only when the charge air flows
into a cylinder 21, 22, 23 that does not supply the exhaust gas
recirculation device 3.
FIG. 2 shows a simplified diagram of the valve control times of the
inventive internal combustion engine 1. The diagram shows a valve lift
diagram A for all the outlet valves of the cylinders 18, 19, 20, 21, 22,
23, a valve lift diagram B for the intake valves of the cylinders 21, 22,
23 and a valve lift diagram C of the cylinders 18, 19, 20 of the internal
combustion engine. The valve lift diagrams A, B, C are plotted in valve
lift in millimeters as a function of the crank angle in degrees of crank
angle.
In addition or as an exclusive measure for the inventive internal
combustion engine 1 illustrated in FIG. 1, the valve control times of the
cylinders 18, 19, 20 supplying the exhaust gas recirculation device 3 are
varied in the manner according to this invention so that the intake valves
and outlet valves of the cylinders 18, 19, 20 supplying the exhaust gas
recirculation device 3 have shorter valve overlap times or none at all in
comparison with the cylinders 21, 22, 23 that do not supply the exhaust
gas recirculation device 3. As shown in the diagram, the valve control
times of all the outlet valves always remain unchanged while the valve
control times of the inlet valves of the cylinders 18, 19, 20 which supply
the exhaust gas recirculation device 3 are retarded by 5.degree. of crank
angle. The inner exhaust gas recirculation in the case of the cylinders
18, 19, 20 which supply the exhaust gas recirculation device 3 is
advantageously significantly reduced even at a negative purging gradient.
It is thus possible to counteract the overproportional internal exhaust gas
recirculation on the cylinders 18, 19, 20 that supply the exhaust gas
recirculation device 3 and to uniformly distribute the emissions over all
the cylinders of the internal combustion engine. In contrast with that,
the exhaust gas recirculated through the exhaust gas recirculation device
3 in the case of the internal combustion engine 1 according to FIG. 1 is
divided differently among the individual cylinders 18, 19, 20, 21, 22, 23
of the internal combustion engine 1 in order to distribute the emissions
uniformly over all the cylinders of the internal combustion engine.
The foregoing disclosure has been set forth merely to illustrate the
invention and is not intended to be limiting. Since modifications of the
disclosed embodiments incorporating the spirit and substance of the
invention may occur to persons skilled in the art, the invention should be
construed to include everything within the scope of the appended claims
and equivalents thereof.
*
