U.S. patent application number 10/573184 was filed with the patent office on 2007-07-19 for internal combustion engine with exhaust treatment system.
Invention is credited to Thomas Hofmann, Ulrich Meingast.
Application Number | 20070163239 10/573184 |
Document ID | / |
Family ID | 34306270 |
Filed Date | 2007-07-19 |
United States Patent
Application |
20070163239 |
Kind Code |
A1 |
Hofmann; Thomas ; et
al. |
July 19, 2007 |
Internal combustion engine with exhaust treatment system
Abstract
An internal combustion engine has an exhaust treatment system
for reducing pollutants in the exhaust. The system includes a
reservoir containing an active ingredient a delivery device for
delivering the active ingredient and an injection device for
injecting the active ingredient into the exhaust. According to the
present invention, the exhaust treatment system includes a pressure
reservoir that is fed by the delivery device; this pressure
reservoir is able to store the active ingredient under pressure and
is directly connected to the injection device.
Inventors: |
Hofmann; Thomas; (Leonberg,
DE) ; Meingast; Ulrich; (Stuttgart, DE) |
Correspondence
Address: |
RONALD E. GREIGG;GREIGG & GREIGG P.L.L.C.
1423 POWHATAN STREET, UNIT ONE
ALEXANDRIA
VA
22314
US
|
Family ID: |
34306270 |
Appl. No.: |
10/573184 |
Filed: |
July 28, 2004 |
PCT Filed: |
July 28, 2004 |
PCT NO: |
PCT/DE04/01692 |
371 Date: |
November 1, 2006 |
Current U.S.
Class: |
60/286 ; 60/295;
60/301 |
Current CPC
Class: |
Y02T 10/24 20130101;
Y02T 10/12 20130101; B01D 53/9495 20130101; F01N 3/208 20130101;
F01N 2610/10 20130101; F01N 2610/02 20130101 |
Class at
Publication: |
060/286 ;
060/295; 060/301 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Sep 23, 2003 |
DE |
103 46 220.1 |
Claims
1-12. (canceled)
13. An internal combustion engine, in particular with fuel direct
injection, having an exhaust treatment system for reducing
pollutants in the exhaust, the exhaust treatment system comprising
a reservoir containing an active ingredient, a delivery device for
delivering the active ingredient, an injection device for injecting
the active ingredient into the exhaust, and a pressure reservoir
that is fed by the delivery device the pressure reservoir being
able to store the active ingredient under pressure and being
directly connected to the injection device.
14. The internal combustion engine according to claim 13, wherein
the delivery device comprises a presupply pump and a high pressure
pump.
15. The internal combustion engine according to claim 13, further
comprising a pressure regulating device connected to the pressure
reservoir.
16. The internal combustion engine according to claim 14, further
comprising a pressure regulating device connected to the pressure
reservoir.
17. The internal combustion engine according to claim 13, further
comprising a control and/or regulating device, which controls
and/or regulates the delivery capacity (M_DD) of the delivery
device, the pressure (PR_UPR) in the pressure reservoir, the time
at which the injection of the active ingredient occurs, and/or the
duration (TI_UID) of an injection of the active ingredient as a
function of the operating state (N, RA, RF, TMOT, LAMBDA) of the
internal combustion engine.
18. The internal combustion engine according to claim 16, further
comprising a control and/or regulating device, which controls
and/or regulates the delivery capacity (M_DD) of the delivery
device, the pressure (PR_UPR) in the pressure reservoir, the time
at which the injection of the active ingredient occurs, and/or the
duration (TI_UID) of an injection of the active ingredient as a
function of the operating state (N, RA, RF, TMOT, LAMBDA) of the
internal combustion engine.
19. The internal combustion engine according to claim 13, wherein
the delivery device, the pressure reservoir, and/or the injection
device are of the type used in direct-injecting, fuel systems.
20. The internal combustion engine according to claim 16, wherein
the delivery device, the pressure reservoir, and/or the injection
device are of the type used in direct-injecting fuel systems.
21. The internal combustion engine according to claim 17, wherein
the delivery device, the pressure reservoir, and/or the injection
device are of the type used in direct-injecting fuel systems.
22. The internal combustion engine according to claim 13, wherein
the active ingredient is urea.
23. The internal combustion engine according to claim 16, wherein
the active ingredient is urea.
24. The internal combustion engine according to claim 17, wherein
the active ingredient is urea.
25. The internal combustion engine according to claim 22, further
comprising means to heat the pressure reservoir.
26. A method for operating an internal combustion engine according
to claim 13, wherein the delivery capacity (M_DD) of the delivery
device, the pressure (PR_UPR) in the pressure reservoir, the time
at which the injection of the active ingredient occurs, and/or the
duration (TI_UID) of the injection of the active ingredient depend
on the current operating parameters (N, RA, RF, TMOT, TASP, HASP,
TSCR, NOX, LAMDA) of the internal combustion engine.
27. A method for operating an internal combustion engine according
to claim 17, wherein the delivery capacity (M_DD) of the delivery
device, the pressure (PR_UPR) in the pressure reservoir, the time
at which the injection of the active ingredient occurs, and/or the
duration (TI_UID) of the injection of the active ingredient depend
on the current operating parameters (N, RA, RF, TMOT, TASP, HASP,
TSCR, NOX, LAMDA) of the internal combustion engine.
28. The method according to claim 26, wherein the operating
parameters include a speed (N) of a crankshaft, a torque of the
engine, a fuel mass (RF) injected into a combustion chamber, a
temperature (TMOT) of the engine, a temperature (TASP) of the
ambient air, a humidity (HASP) of the ambient air, a temperature
(TSCR) before and/or after a catalytic converter, an NO.sub.x,
and/or NH.sub.3 content (NOX) in the exhaust, and/or a fuel/air
ratio (LAMBDA) in the combustion chamber or an equivalent value
(RA).
29. A computer program, characterized in that it is programmed to
be used in a method according to claim 26.
30. A computer program, characterized in that it is programmed to
be used in a method according to claim 26.
31. An electric storage medium for a control and/or regulating unit
of an internal combustion engine, operable to store a computer
program to be used in a method according to claim 26.
32. A control and/or regulating unit for an internal combustion
engine, the unit being programmed to be used to perform the method
according to claim 26.
Description
PRIOR ART
[0001] The invention relates first to an internal combustion
engine, in particular equipped with fuel direct injection, having
an exhaust treatment system for reducing pollutants in the exhaust,
which includes: a reservoir containing a fluid active ingredient, a
delivery device for delivering the active ingredient, and an
injection device for injecting the active ingredient into the
exhaust.
[0002] There is a need for reducing nitrogen oxide emissions from
motor vehicles, particularly in light of legal requirements
expected in future. In order to reduce nitrogen oxide emissions
from internal combustion engines, for example those with gasoline
or diesel direct injection, so-called selective catalytic reduction
(SCR) can be used. This process introduces a definite quantity of a
reducing agent, in particular urea, into an exhaust line. Since
urea is solid under normal environmental conditions, it is supplied
in the form of a urea/water solution that is injected into the
exhaust. In a first reaction stage, the urea reacts with water to
produce ammonia and carbon dioxide. In a second reaction stage, the
ammonia reduces the nitrogen oxides contained in the exhaust to
nitrogen, with water produced as a byproduct.
[0003] DE 101 39 142 A1 has disclosed an exhaust treatment system
for an internal combustion engine in which a pump supplies a
urea/water solution from a reservoir to a mixing chamber in which
compressed air is used to produce an aerosol that is then injected
into the exhaust of the internal combustion engine.
[0004] The object of the present invention is to improve the
efficiency of the exhaust treatment.
[0005] This object is attained in an internal combustion engine of
the kind mentioned at the beginning in that the exhaust treatment
system has a pressure reservoir into which the delivery device
feeds; this pressure reservoir is able to store the active
ingredient under pressure and is directly connected to the
injection device.
ADVANTAGES OF THE INVENTION
[0006] A first advantage of the internal combustion engine
according to the present invention is that because of the elevated
pressure in the pressure reservoir, which is then in principle also
present in the injection device, the injection device is able to
atomize the active ingredient particularly well, thus imparting a
good preparation quality to the resulting spray. This leads to an
improved conversion rate of the active ingredient in the exhaust.
The temporary storage of the active ingredient in the pressure
reservoir also permits the optional use of a delivery device with a
lower delivery capacity since "consumption peaks" in a
corresponding system configuration can be covered not by an
increased delivery capacity but by the active ingredient
temporarily stored in the pressure reservoir.
[0007] Advantageous modifications of the present invention are
disclosed in the dependent claims.
[0008] In a first embodiment, the delivery device includes a
presupply pump and a high-pressure pump. The presupply pump can,
for example, be a diaphragm pump and the high-pressure pump can be
a piston pump. This makes it possible to achieve particularly high
pressures in the pressure reservoir, which in turn results in a
particularly good atomization of the active ingredient during
injection into the exhaust.
[0009] It is also advantageous if the pressure reservoir is
connected to a pressure regulating device. This either permits a
high degree of pressure constancy or, with an adjustable pressure
regulating device, enables the pressure in the pressure reservoir
to be varied, which permits an optimal adaptation of the pressure
the pressure reservoir to the current operating state of the
exhaust treatment system and/or the internal combustion engine.
[0010] A particularly advantageous embodiment of the internal
combustion engine according to present invention has a control
and/or regulating unit that controls and/or regulates the delivery
capacity of the delivery device, the pressure in the pressure
reservoir, the time at which the injection of the active ingredient
occurs, and/or the duration of the injection of the active
ingredient as a function of the operating state of the internal
combustion engine. This permits a particularly economical
consumption of the active ingredient with a simultaneously optimal
conversion rate of the active ingredient in the exhaust.
[0011] The costs for the internal combustion engine according to
present invention can be reduced if the delivery device, the
pressure reservoir, and/or the injection device are of the type
used in direct-injecting fuel systems. In particular, these include
the fuel systems that operate with a fuel accumulator ("common
rail"). It may be necessary to select those systems whose delivery
devices are not lubricated by the fluid delivered.
[0012] Another embodiment is distinguished by the fact that the
active ingredient is urea. In general, the urea here is bound in an
aqueous solution and is not dangerous, but permits an effective
reduction of nitrogen oxides in the exhaust.
[0013] In a modified embodiment, it is possible to heat the
pressure reservoir. The urea/water solution usually used has the
property of freezing, i.e. changing from the fluid to the solid
state, at temperatures below -11.degree. C. The ability to heat the
pressure reservoir assures the functionality of the exhaust
treatment system even at such low temperatures.
[0014] The present invention also relates to a method for operating
an internal combustion engine of the type mentioned above. The
delivery capacity of the delivery device, the pressure in the
pressure reservoir, the time at which the injection of the active
ingredient occurs, and/or the duration of the injection of the
active ingredient depend on the current operating state of the
internal combustion engine. This permits a particularly effective
reduction in pollutant emissions in the exhaust with a
simultaneously low consumption of the active ingredient.
[0015] In a modified embodiment, the operating parameters include a
speed of a crankshaft, a torque of the engine, a fuel mass injected
into a combustion chamber, a temperature of the engine, a
temperature of the ambient air, a humidity of the ambient air, a
temperature before and/or after a catalytic converter, an NO.sub.x,
and/or NH.sub.3 content in the exhaust, and/or a fuel/air ratio in
the combustion chamber, or an equivalent value. In many internal
combustion engines, these operating parameters are detected anyway
so that no additional sensors are required in order to use them,
which reduces the costs of the engine. Primarily, the use of an
NO.sub.x, or NH.sub.3 content in the exhaust permits a regulated
metering of the active ingredient and possibly even an adaptation
of the models used for the metering.
[0016] The corresponding control and/or regulation algorithms have
usually already been worked out since the input and output values
required for calculating the metered quantities are used in a
similar form in the context of fuel direct injection and are thus
already on hand. It is also conceivable that the calculation and
application of the data required for the injection or metering of
the active ingredient can be determined based on characteristic
maps of the internal combustion engine. This could save on the cost
of an additional control unit and certain quantity corrections
could be carried out in parallel based on corresponding correction
coefficients that are calculated as part of the process of
controlling the engine.
DRAWINGS
[0017] A particularly preferred exemplary embodiment of the present
invention will be explained in detail below in conjunction with the
accompanying drawings.
[0018] FIG. 1 shows a schematic diagram of an internal combustion
engine with an exhaust treatment system; and
[0019] FIG. 2 shows the input and output values for controlling and
regulating the exhaust treatment system from FIG. 1.
DESCRIPTION OF THE EXEMPLARY EMBODIMENT
[0020] FIG. 1, an internal combustion engine is labeled as a whole
with the reference numeral 10. It has a number of combustion
chambers, only one of which--labeled with the reference numeral
12--is shown in FIG. 1 for the sake of clarity. Combustion air
travels into the combustion chamber 12 via an inlet valve 14 and an
intake tube 16. Sensors 15 and 17 detect a temperature TASP and a
humidity HASP of the aspirated ambient air. The hot combustion
gases are conveyed out of the combustion chamber 12 via an outlet
valve 18 and an outlet tube 20. During operation, a crankshaft 21
is set into rotation. A fuel injection device 22 delivers fuel
directly into the combustion chamber 12.
[0021] The injected fuel in the current exemplary embodiment is
diesel fuel. The fuel injection device 22 is connected to a fuel
accumulator 24 ("rail"). The fuel is stored at high pressure in
this rail. A presupply pump 28 delivers fuel from a fuel tank 30 to
a high-pressure fuel pump 26, which then delivers it to the fuel
accumulator 24. A sensor 32 detects the pressure in the fuel
accumulator 24 and a pressure regulator 34 adjusts this pressure. A
quantity control valve 36 adjusts the delivery quantity of the
high-pressure fuel pump 26. The above-mentioned components 22
through 36 are part of a fuel system 37.
[0022] The internal combustion engine 10 is equipped with an
exhaust treatment system 38 in order to reduce pollutant emissions
in its exhaust. This system includes an oxidation converter 39,
which is situated in the exhaust line 20 and converts NO into
NO.sub.2, and a catalytic converter 40 that then reduces pollutants
in the exhaust. Upstream of the catalytic converter 40, the exhaust
line 20 contains a temperature sensor 41 for detecting the
temperature TSCR of the exhaust and an injection device 42 that is
able to inject an active ingredient, urea 43 in the present
exemplary embodiment, into the exhaust flowing through the exhaust
line 20. To this end, the urea is dissolved in water, i.e. the
final step is the injection of a urea/water solution. Downstream of
the catalytic converter 40, there is a lambda probe 45 and an
NO.sub.x sensor 47.
[0023] The urea/water solution 43 is stored in a urea receptacle
44. A presupply pump 46 feeds the urea/water solution 43 from the
urea receptacle 44 to a high-pressure pump 48 (the two pumps 46 and
48 together constitute a delivery device 49). This device
compresses the urea/water solution 43 to a very high pressure and
delivers it to a urea pressure reservoir 50, which can be tubular
or spherical, for example, and is in turn connected to the
injection device 42.
[0024] A pressure sensor 52 detects the pressure in the urea
pressure reservoir 50. A pressure regulator 54 adjusts the pressure
in the pressure reservoir 50 and a quantity control valve 56
adjusts the delivery quantity of the high-pressure urea pump 48.
All the components of the exhaust treatment system 38 except for
the catalytic converter 40 and the injection device 42 can be
heated by an electrical heating unit 58.
[0025] A control and/or regulating unit 60 controls and/or
regulates the operation of the internal combustion engine 10,
including the operation of the fuel system 37. It receives signals
from numerous sensors, for example the two pressure sensors 32 and
52, as well as from additional sensors not shown in FIG. 1, and
controls the corresponding adjusting and regulating devices, for
example the injection devices 22 and 42, the quantity control
valves 36 and 56, and the pressure regulators 34 and 54, as a
result of which the internal combustion engine 10 generates a
desired output with the lowest possible fuel consumption and an
optimal emissions behavior. The control and regulating unit 60 also
controls and/or regulates the operation of the exhaust treatment
system 38.
[0026] As is clear from FIG. 2, various input values are fed into a
processing block 62. These include a speed N of the crankshaft 21,
a relative air charge RA in the combustion chamber 12, a relative
fuel mass RF injected into the combustion chamber 12 by the fuel
injection device 22, a temperature TMOT of the engine 10 (e.g. a
cooling water temperature or a cylinder head temperature), and the
fuel/air ratio in the combustion chamber 12, which is represented
by the air number LAMBDA. Other values can include a temperature
TSCR of the catalytic converter 40, a relative humidity HASP of the
aspirated air, for example a temperature TASP of the ambient air,
or an NO.sub.x, value.
[0027] Based on these values, control variables required for
operating the exhaust treatment system 38 are determined in the
processing block 62. These include a pressure PR_UPR in the urea
pressure reservoir 50, a triggering voltage U_UPR for the quantity
control valve 56, which in turn adjusts a delivery quantity M_UPR
for the delivery device 49, an injection duration TI_UPR of the
injection device 42 for the urea 43, and a bit B_HEAT that turns
the heating unit 58 on and off.
[0028] Is clear that in the internal combustion engine 10, the
operation of the exhaust treatment system 38 is essentially
controlled by means of operating values of the engine 10. The
pressure PR_UPR in the urea pressure reservoir 50 and the injection
duration TI_UPR of the urea injection device 42 can be used to
adapt the injected quantity on the one hand and the degree of
atomization of the urea/water solution 43 on the other to the
current operating requirements of the internal combustion engine
10. On the one hand, this assures an optimal conversion of the
injected urea/water solution 43, which leads to a reduction in
pollutant emissions, and on the other, the urea/water solution 43
can be used very economically since it is possible to avoid
generating too much ammonia, but at the same time to assure an
almost 100% conversion rate.
[0029] Similar to the fuel system 37, the pressure in the urea
pressure reservoir 50 can be very high and can lie in the range
above 50 bar, if need be even in a range from a few hundred bar to
over a thousand bar. The components used for the exhaust treatment
system 38 can be similar to the components of the fuel system 37.
It is also possible, at least in some regions, to use components
identical to those of the fuel system 37. In addition, the
processing model used in the processing block 62 can resemble or
even be identical to the one used to control and/or regulate the
fuel system 37. In the processing block 62, usually the pressure
PR_UPR depends primarily on the speed N of the crankshaft 21 and on
the temperature TSCR of the exhaust. At a constant speed, the
pressure regulator 54 and the quantity control valve 56 can be used
to set a constant pressure in the urea pressure reservoir 50.
[0030] In the exemplary embodiment depicted in FIG. 1, the urea
injection device 42 injects the urea/water solution 43 directly
into the exhaust line 20. However, it is also possible for air to
be fed into the urea injection device 42 and for this air to be
mixed with the urea/water solution 43 either inside the urea
injection device 42 or upon exiting from it.
[0031] In the present exemplary embodiment, the active ingredient
is referred to as urea 43. Naturally, however, the above-described
embodiment of the exhaust treatment system 38 can use any other
substance as the active ingredient, as long as this substance can
be injected into the exhaust. For example, this could include the
injection of diesel fuel, or in the most general sense, HC, or also
the injection of gaseous or powdered substances.
[0032] It should also be noted that in the context of the preceding
specification, different components have been referred to for short
as merely "urea" components (e.g. the "urea pressure reservoir")
despite the fact that in the exemplary embodiment described above,
pure urea was naturally not used but instead always a urea/water
solution.
* * * * *