U.S. patent application number 10/169169 was filed with the patent office on 2003-07-24 for method of operating an internal combustion engine in particular in a motor vehicle.
Invention is credited to Bellmann, Holger, Blumenstock, Andreas, Koring, Andreas, Schnaibel, Eberhard, Schumann, Bernd, Stanglmeier, Frank, Wahl, Thomas, Winkler, Klaus.
Application Number | 20030136114 10/169169 |
Document ID | / |
Family ID | 7935102 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030136114 |
Kind Code |
A1 |
Schnaibel, Eberhard ; et
al. |
July 24, 2003 |
Method of operating an internal combustion engine in particular in
a motor vehicle
Abstract
An internal combustion engine (1), in particular for a motor
vehicle, is described; it is equipped with a catalytic converter
(12) which may be exposed to nitrogen oxides. A lambda probe (13)
is provided for measuring the oxygen concentration downstream from
the catalytic converter (12). The nitrogen oxides supplied to the
catalytic converter (12) are increased by a controller (18), and
the conversion capacity of the catalytic converter (12) is
concluded from the increase in oxygen concentration downstream from
the catalytic converter (12).
Inventors: |
Schnaibel, Eberhard;
(Hemmingen, DE) ; Koring, Andreas; (Ludwigsburg,
DE) ; Bellmann, Holger; (Ludwigsburg, DE) ;
Wahl, Thomas; (Pforzheim, DE) ; Blumenstock,
Andreas; (Ludwigsburg, DE) ; Winkler, Klaus;
(Rutesheim, DE) ; Stanglmeier, Frank; (Moglingen,
DE) ; Schumann, Bernd; (Rutesheim, DE) |
Correspondence
Address: |
KENYON & KENYON
ONE BROADWAY
NEW YORK
NY
10004
US
|
Family ID: |
7935102 |
Appl. No.: |
10/169169 |
Filed: |
November 5, 2002 |
PCT Filed: |
December 23, 2000 |
PCT NO: |
PCT/DE00/04655 |
Current U.S.
Class: |
60/285 ;
60/301 |
Current CPC
Class: |
F01N 2570/14 20130101;
F02D 41/1408 20130101; Y02A 50/20 20180101; Y02T 10/40 20130101;
F02D 2200/0811 20130101; F01N 3/0842 20130101; F01N 11/007
20130101; F02D 41/0275 20130101 |
Class at
Publication: |
60/285 ;
60/301 |
International
Class: |
F01N 003/00; F01N
003/10 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 31, 1999 |
DE |
199-63-936.1 |
Claims
What is claimed is:
1. A method of operating an internal combustion engine (1), in
particular in a motor vehicle, a catalytic converter (12) being
exposed to nitrogen oxides, and the oxygen concentration (O2free)
downstream from the catalytic converter (12) being measured,
wherein the nitrogen oxides supplied to the catalytic converter
(12) are increased, and the conversion capacity of the catalytic
converter (12) is concluded from the increase in the oxygen
concentration (O2free) downstream from the catalytic converter
(12).
2. The method according to claim 1, wherein the oxygen
concentration (O2Exhaust) upstream from the catalytic converter
(12) is kept constant.
3. The method according to one of claims 1 or 2, wherein the lambda
value upstream from the catalytic converter (12) is kept
constant.
4. The method according to claim 2 or 3, wherein the measured
oxygen concentration (O2free) downstream from the catalytic
converter (12) represents the oxygen concentration (O2Cat) released
by the catalytic converter (12) from the nitrogen oxides
supplied.
5. The method according to one of claims 1 through 4, wherein the
concentration (O2Cat) is used as a measure of the conversion
capacity of the catalytic converter (12).
6. The method according to one of claims 1 through 5, wherein the
increase in nitrogen oxides supplied to the catalytic converter
(12) is achieved by detuning the ignition time and/or through other
measures in the control and/or regulation of the internal
combustion engine (1).
7. A control element, in particular a flash memory, for a
controller (18) of an internal combustion engine (1) in a motor
vehicle in particular, a program being stored on it, capable of
running on a computer, in particular a microprocessor, and suitable
for execution of a method according to one of claims 1 through
6.
8. A controller (18) for an internal combustion engine (1) of a
motor vehicle in particular, the engine (1) having a catalytic
converter (12) which may be exposed to nitrogen oxides, and having
a lambda probe (13) for measuring the oxygen concentration (O2free)
downstream from the catalytic converter (12), wherein the
controller (18) is capable of increasing the nitrogen oxides
supplied to the catalytic converter (12), and the controller (18)
is capable of determining the conversion capacity of the catalytic
converter (12) on the basis of the increase in oxygen concentration
(O2free) downstream from the catalytic converter (12).
9. An internal combustion engine (1) for a motor vehicle in
particular, having a catalytic converter (12) which may be exposed
to nitrogen oxides, and having a lambda probe (13) for measuring
the oxygen concentration (O2free) downstream from the catalytic
converter (12) and having a controller (18), wherein the controller
(18) is capable of increasing the nitrogen oxides supplied to the
catalytic converter (12) and of concluding the conversion capacity
of the catalytic converter (12) on the basis of the increase in
oxygen concentration (O2free) downstream from the catalytic
converter (12).
Description
BACKGROUND INFORMATION
[0001] The present invention relates to a method of operating an
internal combustion engine of a motor vehicle in particular, a
catalytic converter being exposed to nitrogen oxides, and the
oxygen concentration being measured downstream from the catalytic
converter. Likewise the present invention also concerns a
controller for an engine of a motor vehicle in particular as well
as an engine for a motor vehicle in particular.
[0002] Such a method, such a controller and such an engine are
known, for example, with intake manifold injection, where fuel is
injected into the intake manifold of the engine during the intake
phase. Nitrogen oxides resulting from combustion of fuel are
converted to nitrogen and oxygen in the catalytic converter. The
catalytic converter is known to be subject to aging, which causes a
decline in conversion capacity.
[0003] A method of the type defined above is also known for an
internal combustion engine having direct injection. In this case,
fuel is injected directly into the combustion chamber of the engine
during the intake phase. The resulting nitrogen oxides are
optionally stored temporarily in the downstream catalytic
converters and then converted to oxygen.
OBJECT AND ADVANTAGES OF THE INVENTION
[0004] The object of the present invention is to create a method of
operating an engine with which the aging of the catalytic converter
is detectable.
[0005] This object is achieved by a method according to the present
invention of the type defined in the preamble by increasing the
nitrogen oxides supplied to the catalytic converter, and
determining the conversion capacity of the catalytic converter from
an increase in oxygen concentration downstream from the catalytic
converter. The object is achieved accordingly with a controller and
an internal combustion engine of the type defined in the preamble.
The present invention is equally applicable with intake manifold
injection and with an engine having direct fuel injection.
[0006] Increasing the nitrogen oxides supplied to the catalytic
converter results in increased conversion of nitrogen oxides to
nitrogen and oxygen. The resulting increase in oxygen concentration
downstream from the catalytic converter is measured. The conversion
capacity of the catalytic converter may be concluded from this
increase.
[0007] With a new catalytic converter, the conversion capacity is
high and the increase in oxygen concentration will also be high.
With an aged catalytic converter, however, the increase in oxygen
concentration will be diminished due to the diminished conversion
capacity. This may be used as a measure of the conversion capacity
and thus the aging of the catalytic converter.
[0008] Therefore, with the method according to the present
invention for detecting the aging of the catalytic converter, no
NOx sensor is necessary. This is a considerable cost saving.
Likewise the required lambda probe for measuring the oxygen
concentration downstream from the catalytic converter may also be
used for other purposes, e.g., for controlling and/or regulating
the engine, in particular for setpoint control, as it is known.
[0009] In an advantageous refinement of the present invention, the
oxygen concentration upstream from the catalytic converter is kept
constant. This achieves the result that only the elevated nitrogen
oxide concentrations result in an increase in oxygen concentration
downstream from the catalytic converter. However, the composition
of the exhaust gas with respect to other components has no effect
on the conclusion of catalytic converter conversion capacity
according to the present invention.
[0010] In another advantageous refinement of the present invention,
the lambda value is kept constant upstream from the catalytic
converter. This also results in that only the elevated nitrogen
oxides result in an increase in oxygen concentration downstream
from the catalytic converter. This greatly simplifies the method
according to the present invention.
[0011] In an advantageous embodiment of the present invention, the
measured oxygen concentration downstream from the catalytic
converter represents the oxygen concentration released by the
catalytic converter from the nitrogen oxides supplied. This allows
an especially simple and effective method of determining the
conversion capacity of the catalytic converter.
[0012] It is especially advantageous if the increase in nitrogen
oxides supplied to the catalytic converter is achieved by detuning
of the ignition time and/or other interventions in the control
and/or regulation of the engine. These options for modifying the
nitrogen oxide feed to the catalytic converter are especially
simple to implement and nevertheless very accurate. Repetition of
the method according to the present invention and thus continuous
diagnosis of the catalytic converter are thus readily possible.
[0013] Implementation of the method according to the present
invention in the form of a control element provided for a
controller of an engine in a motor vehicle in particular is
particularly important. A program capable of running on a computer,
in particular a microprocessor, and suitable for execution of the
method according to the present invention is stored in the control
element. In this case, the present invention is implemented via a
program stored in the control element so that this control element
equipped with the program represents the present invention in the
same manner as the method for whose execution the program is
suitable. An electric storage medium e.g., a read-only memory or a
flash memory, may be used in particular as the control element.
[0014] Other features, possible applications, and advantages of the
present invention are derived from the following description of
exemplary embodiments of the invention illustrated in the drawing.
All the features described or illustrated here form the object of
the present invention either independently or in any desired
combination, regardless of how they are combined in the patent
claims or their reference back to a previous claim and regardless
of how they are formulated in the description or illustrated in the
drawing.
EXEMPLARY EMBODIMENTS OF THE INVENTION
[0015] The sole FIGURE in the drawing shows a schematic
illustration of an embodiment of an engine according to the present
invention.
[0016] The FIGURE shows an internal combustion engine 1 in a motor
vehicle, where a piston 2 is movable back and forth in a cylinder
3. Cylinder 3 is equipped with a combustion chamber 4, which is
delimited by piston 2, intake valve 5, and exhaust valve 6. An
intake manifold 7 is connected to intake valve 5 and an exhaust
pipe 8 is connected to exhaust valve 6.
[0017] An injector 9 is provided in intake manifold 7. A spark plug
10 protrudes into combustion chamber 4 in the area of intake valve
5 and exhaust valve 6. Fuel may be injected into intake manifold 7
through injector 9. The air/fuel mixture drawn in may be ignited in
combustion chamber 4 by spark plug 10.
[0018] A rotatable throttle valve 11 is accommodated in intake
manifold 7. The amount of air supplied to combustion chamber 4
depends on the angular setting of throttle valve 11. A catalytic
converter 12 is provided in exhaust pipe 8 to purify the exhaust
gas generated by combustion of fuel.
[0019] Catalytic converter 12 is provided so that nitrogen oxides
(NOx) may be converted to nitrogen and oxygen. A continuous lambda
probe 13 is provided in the exhaust pipe directly downstream from
catalytic converter 12 and is suitable for measuring the free
oxygen concentration O2free in the exhaust downstream from
catalytic converter 12.
[0020] A controller 18 receives input signals 19 which are
operating variables of engine 1 measured by sensors. Controller 18
generates output signals 20 with which the performance of engine 1
may be influenced via actuators and controlling elements.
Controller 18 is provided so that, among other things, the
operating variables of engine 1 may be controlled and/or regulated.
To this end, controller 18 is equipped with a microprocessor which
has a program suitable for executing this control and/or regulation
stored in a memory medium, in particular in a flash memory.
[0021] Nitrogen oxides (NOx) generated during operation of engine 1
are supplied to catalytic converter 12. These nitrogen oxides are
converted by catalytic converter 12 into nitrogen and oxygen. The
ongoing conversion results in a diminished conversion capacity of
catalytic converter 12; this is referred to hereinafter as
aging.
[0022] Free oxygen concentration O2free downstream from catalytic
converter 12 is composed of oxygen concentration O2Exhaust in the
exhaust gas downstream from catalytic converter 12 and oxygen
concentration O2Cat released from the nitrogen oxide feed by
catalytic converter 12. Concentration O2Exhaust is in the per mill
range, and concentration O2Cat is approximately in the ppm
range.
[0023] Oxygen concentration O2Exhaust in the exhaust gas downstream
from catalytic converter 12 depends on the oxygen concentration
upstream from the catalytic converter and thus on the lambda value
upstream from catalytic converter 12. For performing the diagnosis
of catalytic converter 12 described below, the oxygen concentration
upstream from catalytic converter 12 and thus the lambda value
upstream from catalytic converter 12 are kept constant. The oxygen
concentration O2Exhaust in the exhaust gas downstream from
catalytic converter 12 is therefore constant.
[0024] Then the concentration or number of nitrogen oxides upstream
from catalytic converter 12 is increased. This may be accomplished,
for example, by detuning the ignition time of individual cylinders
or by similar measures.
[0025] Because of the increased nitrogen oxide concentration
upstream from catalytic converter 12, an increased conversion of
nitrogen oxides to nitrogen and oxygen is performed by same. This
results in an increased oxygen concentration O2Cat released from
the nitrogen oxide feed by catalytic converter 12. This increased
concentration O2Cat in turn results in an increased free oxygen
concentration O2free downstream from catalytic converter 12.
[0026] Increased free oxygen concentration O2free downstream from
catalytic converter 12 is measured by continuous lambda probe 13
downstream from catalytic converter 12. Since oxygen concentration
O2Exhaust in the exhaust gas downstream from catalytic converter 12
is kept constant, increased free oxygen concentration O2free
measured by lambda probe 13 represents directly the increase in
oxygen concentration O2Cat released from the nitrogen oxide feed by
catalytic converter 12.
[0027] The diagnostic method described above is performed by
controller 18 at preselected intervals in time and/or on the basis
of preselected events. This results in a series of successive
measurement results for increased concentration O2free representing
the increase in concentration O2Cat, as stated above.
[0028] As already mentioned, the conversion capacity of catalytic
converter 12 declines over time due to aging. This decline in
conversion capacity results in concentration O2Cat also declining
over time in the measurement results performed as described above.
Concentration O2Cat is to this extent a measure of the conversion
capacity and thus the aging of catalytic converter 12.
[0029] Finally, controller 18 concludes the conversion capacity and
thus the aging of catalytic converter 12 on the basis of the
individual measurement results and the curve of successive
measurement results for concentration O2free. This is achieved, for
example, by monitoring the change in concentration O2free. It is
likewise possible to monitor the absolute values of concentration
O2free and to compare them with the values of a new catalytic
converter, for example. All these comparisons may be performed by
controller 18 either individually or in combination. Thus, on the
whole, it is possible for controller 18 to conclude the aging or
aging condition of catalytic converter 12. If this aging exceeds a
preselected threshold value, this is indicated to the operator of
engine 1 by controller 18.
* * * * *