U.S. patent application number 11/578383 was filed with the patent office on 2007-09-13 for method and device for introducing a reagent into an exhaust gas channel of an internal combustion engine.
This patent application is currently assigned to Robert Bosch GMBH. Invention is credited to Markus Buerglin, Goetz Flender, Franz Lackner, Michael Offenhuber, Wolfgang Ripper, Johann Siller.
Application Number | 20070209349 11/578383 |
Document ID | / |
Family ID | 34961405 |
Filed Date | 2007-09-13 |
United States Patent
Application |
20070209349 |
Kind Code |
A1 |
Ripper; Wolfgang ; et
al. |
September 13, 2007 |
Method And Device For Introducing A Reagent Into An Exhaust Gas
Channel Of An Internal Combustion Engine
Abstract
A procedure to introduce a reagent substance into the exhaust
duct of an internal combustion engine and a device to implement the
procedure are proposed. At least one catalytic converter is
disposed in the exhaust duct of the internal combustion engine. In
front of the aforementioned catalytic converter(s), a reagent
substance subjected to pressure is sprayed into the exhaust gas.
The reagent substance pressure set point is established as a
function of a parameter. The procedural approach allows for a
targeted employment of the reagent substance and a high degree of
utilization of the converter.
Inventors: |
Ripper; Wolfgang;
(Stuttgart, DE) ; Buerglin; Markus; (Ditzingen,
DE) ; Offenhuber; Michael; (Adnet, AT) ;
Flender; Goetz; (Stuttgart, DE) ; Lackner; Franz;
(Flachau, AT) ; Siller; Johann; (Puch Bei Hallein,
AT) |
Correspondence
Address: |
MERCHANT & GOULD PC
P.O. BOX 2903
MINNEAPOLIS
MN
55402-0903
US
|
Assignee: |
Robert Bosch GMBH
Postfach 30 02 20
Stuttgart
DE
70442
|
Family ID: |
34961405 |
Appl. No.: |
11/578383 |
Filed: |
March 14, 2005 |
PCT Filed: |
March 14, 2005 |
PCT NO: |
PCT/EP05/51142 |
371 Date: |
October 12, 2006 |
Current U.S.
Class: |
60/286 ;
60/295 |
Current CPC
Class: |
B01D 53/9495
20130101 |
Class at
Publication: |
060/286 ;
060/295 |
International
Class: |
F01N 3/00 20060101
F01N003/00 |
Foreign Application Data
Date |
Code |
Application Number |
Apr 15, 2004 |
DE |
10 2004 018 221.3 |
Claims
1. A method for the operation of an internal combustion engine, in
whose exhaust area at least one catalytic converters is disposed,
the methods comprising introducing a reagent substance into exhaust
gas before the catalytic converter wherein a pressure of the
reagent substance is determined as a function of a parameter to a
predetermined reagent substance set point.
2. A method according to claim 1, wherein at least one operating
parameter of the internal combustion engine is used as a
parameter.
3. A method according to claim 2, wherein an air signal is used as
the operating parameter of the internal combustion engine.
4. A method according to claim 2, wherein the number of revolutions
per minute and a torque, or the number of revolutions per minute
and a fuel signal are used as operating parameters of the internal
combustion engine.
5. A method according to claim 1, wherein a parameter of the
exhaust gas of the internal combustion engine is used as a
parameter.
6. A method according to claim 5, wherein an exhaust gas speed is
used as the parameter.
7. A method according to claim 5, wherein an exhaust gas pressure
is used as the parameter of the exhaust gas.
8. A method according to claim 5, wherein an exhaust gas
temperature is used as the parameter of the exhaust gas.
9. A method according to claim 5, wherein the parameter of the
exhaust gas is derived from at least one operating parameter of the
internal combustion engine.
10. A method according to claim 1, wherein a reagent substance
temperature is used as the parameter.
11. A method according to claim 1, wherein a pressure of a
compressed air, which is added to a reagent substance in a mixer,
is established as a function of a parameter to a predetermined
compressed air pressure set point.
12. (canceled)
Description
FIELD OF THE INVENTION
[0001] The invention concerns a procedure for the introduction of a
reagent substance in an exhaust duct of an internal combustion
engine and a device for implementation of the procedure according
to the class of the independent claims.
BACKGROUND
[0002] In the German patent DE 101 39 142 A1 an exhaust gas after
treatment system of an internal combustion engine is described;
whereby in order to decrease the NOx emissions, a SCR-catalytic
converter (Selective-Catalytic-Reduction) is employed which reduces
the nitrogen oxides NO and NO.sub.2 with the reducing agent
ammonia. The ammonia is obtained from a urea water solution in an
hydrolysis catalytic converter located upstream from the
SCR-catalytic converter. The hydrolysis catalytic converter
converts the urea contained in the urea water solution to ammonia
and carbon dioxide. To assure an exact metering, provision is made
to ascertain the concentration of the urea water solution.
[0003] The urea water solution is brought to a predetermined
pressure using a pump. A metering valve fixes a predetermined rate
of flow. Compressed air is mixed in with the reagent substance in a
mixing chamber. The urea water solution is sprayed together with
the added air into the exhaust gas in such a way, that a largely
even, consistent flow into the SCR-catalytic converter is achieved.
If need be flow elements like deflection plates are to be
provided.
[0004] From the patent EP 1 024 254 A2 an exhaust gas after
treatment system of an internal combustion engine is made known,
whereby a SCR-catalytic converter is employed to decrease the
NO.sub.x emissions. Provision is made for ammonia to be the
reducing agent, that is obtained in the exhaust duct from a urea
water solution. The amount of urea water solution, which is
measured out, is determined based on an operating parameter of the
internal combustion engine, for example, the amount of fuel
injected and/or the number of revolutions per minute and at least
one parameter of the exhaust, for example the exhaust
temperature.
[0005] In the German patent DE 100 65 105 A1 a procedure is
specified that provides for the modeling of an exhaust temperature
of an internal combustion engine. The exhaust temperature is
calculated as a function of an air signal, that is supplied by an
air sensor and as a function of the number of revolutions per
minute.
[0006] In the professional publication "Otto
engine--Management/Bosch", first edition, published by Vieweg,
Braunschweig, 1998, pages 333-335. A torque structure for operating
an internal combustion engine was made known.
[0007] The task underlying the invention is to specify a procedure
for the introduction of a reagent substance into an exhaust duct of
an internal combustion engine and a device for implementation of
the procedure, which allows for an exact as possible metering of a
reagent substance and a high utilization of the catalytic
converter.
[0008] The task is respectively achieved by way of the
characteristics specified in the independent claims.
SUMMARY
[0009] Provision is made according to the invention, that the
pressure of a reagent substance, which is introduced into the
exhaust of an internal combustion engine upstream of at least one
catalytic converter, is established as a function of a parameter to
a predetermined reagent substance pressure set point.
[0010] The procedural approach of the invention allows for the
achievement of a good atomization and an even, continuous
distribution of the reagent substance in the exhaust gas flow
before at least one catalytic converter. The reagent substance
strikes the entire surface area, which the catalytic converter has
facing the direction of the flow of the exhaust gas. The reagent
substance can, therefore, reach the entire available catalytic
surface area within the catalytic converter. The procedural
approach according to the invention allows, therefore, for the best
possible utilization of the catalytic surface made available by the
catalytic converter. By way of the efficient utilization of the
catalytic converter, the desired cleaning of the exhaust is
achieved with the least possible amount of reagent substance.
[0011] Advantageous embodiments and further configurations of the
procedural approach according to the invention result from
dependent claims.
[0012] An embodiment allows for the use of at least one operating
parameter of the internal combustions engine as a characteristic
parameter. An air signal, for example, is well suited to be an
operating parameter. Additionally or alternatively a torque and/or
a fuel signal can respectively be used in conjunction with the
number of revolutions per minute. The one or more operating
parameters are known to the control unit. Additional sensors will
not be necessary.
[0013] An embodiment allows for the use of one parameter of the
exhaust as the characteristic parameter. The volume of exhaust gas
flow, respectively the exhaust gas speed and/or the exhaust gas
pressure and/or the exhaust gas temperature, is suitable as a
parameter of the exhaust. At a known mass of exhaust gas flow, the
knowledge of the exhaust gas temperature alone is, for example,
sufficient. The one or more parameters of the exhaust gas can be
ascertained from the known operating parameters of the internal
combustion engine. Additional sensors are also not necessary in
this case. If need be, provision can be made for and exhaust gas
temperature sensor to record the exhaust gas temperature. The
measured exhaust gas temperature can be used to authenticate the
calculated exhaust gas temperature.
[0014] An embodiment allows for the reagent substance temperature
to be used as a parameter. The reagent substance temperature can,
for example, be estimated on the basis of a temperature signal of
an existing temperature sensor, which records the air temperature.
Preferably a reagent substance temperature sensor is employed.
[0015] Additional advantageous modifications and embodiments of the
procedural approach according to the invention result from
additional dependent claims and from the following description.
BRIEF DESCRIPTION OF THE DRAWING
[0016] The FIGURE shows an internal combustion engine, in whose
environment a procedure according to the invention is
operating.
[0017] The FIGURE shows an internal combustion engine 10 in whose
intake area and air sensor 11 and in whose exhaust duct 12 a spray
device 13, an exhaust gas temperature sensor 14 as well as a
catalytic converter are disposed.
DESCRIPTION
[0018] The control unit 20 receives at its disposal an air signal
mL supplied by the air sensor 11, a number of revolutions per
minute N supplied by the internal combustion engine 10, an exhaust
gas temperature Tabglw measured by the exhaust gas temperature
sensor 14, a reagent substance pressure actual value pRealw
supplied by a reagent substance pressure sensor 21, a compressed
air pressure actual value pDLlw supplied by a compressed air
pressure sensor 22, a reagent substance temperature TRea supplied
by a reagent substance temperature sensor 23 as well as a torque
set point mifa.
[0019] The control unit 20 emits a fuel signal mK to the internal
combustion engine 10, a metering valve activation signal qRea to a
metering valve 30, a reagent substance pump activation signal 31 to
a reagent substance pump 32 and a compressed air regulating valve
activation signal 33 to a compressed air regulating valve 34.
[0020] The control unit 20 contains a first functional block 41 to
ascertain the exhaust gas speed vabg, a second functional block 42
to ascertain the exhaust gas pressure pabg, a third functional
block 43 to ascertain a calculated exhaust gas temperature TabgR
and a fourth functional block 44 to ascertain a torque Md.
[0021] The control unit 20 additionally contains a reagent
substance pressure set point setting 50, which emits a reagent
substance pressure set point pReaSw to a reagent substance pump
trigger (activation) 51, which supplies the reagent substance pump
activation signal 31, and also contains a compressed air pressure
set point setting 52, which emits a compressed air set point pDLSW
to a compressed air regulating valve trigger (activation) 53, which
supplies the compressed air regulating valve activation signal
33.
[0022] The reagent substance temperature sensor 23 records the
temperature of a reagent substance stored in a reagent substance
container 60. The compressed air regulating valve 34 adjusts the
compressed air set point pDLSw of a compressed air, which is
available in a compressed air container 61.
[0023] The compressed air passes through a super critical choke 62
and a check valve 63 and moves thereafter into a mixer 64, which
mixes the compressed air with the reagent substance introduced by
the metering valve 30. The mixer 64 is connected to the spray
device 13.
[0024] The procedure according to the invention works in the
following manner:
[0025] The catalytic converter 15, which is disposed in the exhaust
area of the internal combustion engine 10 is preferably a
SCR-catalytic converter which reduced the nitrogen oxides NO and
NO.sub.2 contained in the exhaust gas to nitrogen. The
SCR-catalytic converter 15 needs ammonia for the reduction
reaction. The ammonia can be obtained from a urea water solution in
an hydrolysis catalytic converter which is disposed upstream from
the SCR catalytic converter and is not depicted. The solution is
then introduced into the exhaust gas flow with a spray device 13.
The urea water solution is an example of a reagent substance.
[0026] The reagent substance stored in the reagent tank 60 is
brought to the reagent substance pressure set point pReaSw of, for
example, 4 bar by a reagent substance pump 32 and subsequently fed
to the metering valve 30. The amount of reagent substance/unit of
time is predetermined by the metering valve activation signal qRea.
The control unit 20 can ascertain the metering valve activation
signal qRea from a predetermined engine characteristic map, which
is constructed from the number of revolutions per minute N and the
fuel signal mK or which is constructed from the number of
revolutions per minute and the torque Md. The metering valve
activation signal qRea induces the metering valve 30, for example,
to provide clearance of a certain opening width for the reagent
substance. In the mixer 64 the reagent substance is mixed with
compressed air.
[0027] The compressed air is limited to a pressure of, for example,
8 bar in the pressure regulating valve 34. The pressure after the
super critical choke 62 is to be fixed to a value, which is
sufficient enough, that the check valve 63 in front of the mixer 64
is opened and the compressed air can penetrate into the mixer 64.
After passing through the super critical choke 62, a pressure of,
for example, 4.6 bar emerges. Taking into account the pressure drop
at the check valve 63 of, for example, 0.6 bar, the compressed air
pressure in the mixer 64 amounts to ultimately 4 bar.
[0028] The torque Md is established as a function of torque set
point mifa and as a function of known parameters of the internal
combustion engine 10 according to the state of the art named at the
beginning of the application.
[0029] Provision is made according to the invention to preset the
reagent substance pressure set point pReaSw and if need be the
compressed air pressure set point pDLSw. The preset (predetermined)
reagent substance pressure set point pReaSw and if necessary preset
(predetermined) compressed air set point pDLSw are preferably
assessed in such a manner, that after the spray device 13 a good
atomization and an even, continuous distribution of the reagent
substance are achieved over the cross section of the exhaust duct
12. In so doing, the size of the reagent substance droplets play a
role.
[0030] This measure causes the catalytic surface area available to
the SCR-catalytic converter 15 to be completely utilized. It is,
therefore, to be assured, that after the entrance of the reagent
substance into the SCR-catalytic converter, no possibility exists
anymore for its further mixing with the exhaust gas or its
distribution on the catalytic surface area. The procedural approach
according to the invention allows furthermore for a decrease in the
required amount of reduction substance by way of a conforming to
the actual need in the SCR-catalytic converter.
[0031] The pressure of the reagent substance stored in the reagent
substance container 60 can by way of a respective fixing of the
reagent substance pump activation signal 31 in the reagent
substance pump trigger (activation) 51 be brought to a preset
(predetermined) reagent substance set point pReaSw, which, for
example can amount to 4 bar. In order to realize a regulation to
the preset (predetermined) reagent substance pressure set point
pReaSw, the reagent substance pressure actual value pRealw can be
recorded by the reagent substance pressure sensor 21 and then
provided to the reagent substance trigger (activation) 51 for the
implementation of the regulation.
[0032] If need be, the compressed air pressure of the compressed
air built-up in the compressed air container 61 can additionally be
fixed to a preset (predetermined) reagent substance pressure set
point pReaSw before its introduction into the mixing chamber 64. A
compressed air regulating valve 34 is provided for the fixing of
the compressed air pressure. This regulating valve is activated by
the compressed air regulating valve activation signal 33 which is
supplied by the compressed air pressure trigger (activation) 53. In
order to realize a regulation to the preset compressed air pressure
set point pDLSw, the compressed air pressure actual value pDLlw can
be recorded by the compressed air pressure sensor 22 and fed to the
compressed air pressure trigger (activation) 53 to implement the
regulation.
[0033] At least one operating parameter of the internal combustion
engine 10 is suitable as a parameter to establish the reagent
substance set point pDLSw and if need be to establish the
compressed air pressure set point pDLSw. The air signal mL can
already alone be used in this regard. Furthermore, the torque Md as
well as the fuel signal mK are both suitable when used respectively
in combination with the number of revolutions per minute N.
Especially suitable are the last named combinations of at least two
operating parameters mL, mK.
[0034] In an engine characteristic map, which is not depicted, a
one- or multidimensional connection is produced between the
individual operating parameters N, mL, Md, mK and the set point(s)
which is (are) to be preset, namely the reagent substance pressure
set point pReaSw and if need be the compressed air pressure set
point pDLSw.
[0035] The operating parameters N, mL, Md, rnK, which have been
named, have an influence on the parameters of the exhaust gas.
Parameters of the exhaust gas are exhaust gas speed vabg,
respectively the exhaust gas volume flow, the exhaust gas pressure
pabg and, for example, the exhaust gas temperature TabgR, Tabglw.
The parameters vabg, pabg, TabgR of the exhaust gas can be
ascertained in the functional blocks 41, 42, 43, which are
inscribed inside of the control unit 20, from known operating
parameters N, mL, Md, mK.
[0036] The exhaust gas speed vabg can already be ascertained from
the air signal mL in the first functional block 41. If need be, the
fuel signal mK can be taken with it into consideration.
[0037] Using a known geometry of the exhaust gas system and a known
flow resistance of the catalytic converter 15, the exhaust gas
pressure pabg can be ascertained from the exhaust gas speed vabg in
the second functional block 42. The exhaust gas speed vabg and/or
the exhaust gas backpressure pabg are preferably ascertained on the
basis of a two dimensional engine characteristic map, which is
constructed from the number of revolutions per minute N and from
the fuel signal mK or from the number of revolutions per minute N
and from the air signal mL.
[0038] In case provision is made for a turbocharger, the
charging-air pressure and/or charging temperature can be taken into
consideration.
[0039] The exhaust gas temperature TabgR, which is ascertained in
the third functional block 43, has, furthermore, an influence on
the atomization of the reagent substance. The exhaust temperature
TabgR might particularly have an influence on the size of the
droplets of the reagent substance. The ascertainment can, for
example, be carried out according to the German patent DE 100 65
125 A1 named at the beginning of the application, according to
which the exhaust gas temperature TabgR is modeled from the number
of revolutions per minute N and the air signal mL.
[0040] The parameters of the exhaust, which have been described up
till now, are ascertained in the functional blocks 41, 42, 43 from
the operating parameters N, mL, Md, mK of the internal combustion
engine 10. The parameters of the exhaust can be alternatively or
additionally measured with sensors. The exhaust gas temperature
sensor 14 can be employed to measure the exhaust gas temperature,
which passes on the exhaust gas temperature actual value Tabglw to
the control unit 20. Furthermore, the exhaust gas pressure could be
measured with an exhaust gas pressure sensor, which is not
depicted.
[0041] In establishing the reagent substance set point pReaSw and
if need be the establishing of the compressed air pressure set
point pDLSw, the reagent substance temperature TRea, which the
reagent temperature sensor 23 records, can be taken into
consideration. The temperature sensor can be disposed in the
reagent substance tank 60.
[0042] The reagent substance temperature TRea corresponds generally
to the ambient air temperature, which can be measured by a
temperature sensor, which is not depicted. In this case, the
additional reagent substance temperature sensor 23 can be
omitted.
[0043] It is assumed in the depicted example of embodiment, that
the reagent substance is mixed with compressed air in the mixer 64
before being introduced into the exhaust duct 12. The procedural
approach according to the invention can, of course, also be
employed in systems without the support of compressed air. In
systems of this kind, the metering valve 30 can be mounted directly
at the exhaust duct 12, so that the metering valve 30 will be
identical to the spray device 13.
* * * * *