U.S. patent application number 13/055122 was filed with the patent office on 2011-06-02 for method for matching a particle filter temperature adjustment.
This patent application is currently assigned to PEUGEOT CITROEN AUTOMOBILES SA. Invention is credited to Evangelos Georgiadis, Damien Lefebvre.
Application Number | 20110126518 13/055122 |
Document ID | / |
Family ID | 40419130 |
Filed Date | 2011-06-02 |
United States Patent
Application |
20110126518 |
Kind Code |
A1 |
Lefebvre; Damien ; et
al. |
June 2, 2011 |
Method for matching a particle filter temperature adjustment
Abstract
The invention relates to a method for adjusting the temperature
of a particle filter of an exhaust line (1) during a regeneration
phase of said filter by injecting fuel into the exhaust gases, and
which includes the steps of: measuring the temperature (T5) in the
particle filter; predetermining an amount of fuel to inject into
the exhaust gases (Qigec), said amount including a first component
(Qd c) predetermined by means of an open control loop not factoring
in the measured temperature, and said amount including a second
component (Qc2) predetermined by means of a closed control loop
factoring in the measured temperature; and, on the basis of the
amplitude of the second component relative to the predetermined
fuel amount, predetermining a correction term (Kc) of the first
component and applying said correction term in the open control
loop.
Inventors: |
Lefebvre; Damien; (Puteaux,
FR) ; Georgiadis; Evangelos; (Paris, FR) |
Assignee: |
PEUGEOT CITROEN AUTOMOBILES
SA
Velizy Villacoublay
FR
|
Family ID: |
40419130 |
Appl. No.: |
13/055122 |
Filed: |
July 6, 2009 |
PCT Filed: |
July 6, 2009 |
PCT NO: |
PCT/FR2009/051338 |
371 Date: |
January 20, 2011 |
Current U.S.
Class: |
60/274 ;
55/282.3; 60/311 |
Current CPC
Class: |
Y02T 10/40 20130101;
F01N 2610/146 20130101; F01N 3/0253 20130101; F01N 2900/0411
20130101; Y02T 10/47 20130101; F01N 3/035 20130101; F01N 9/002
20130101; F01N 2900/0408 20130101 |
Class at
Publication: |
60/274 ; 60/311;
55/282.3 |
International
Class: |
F01N 3/025 20060101
F01N003/025; F01N 9/00 20060101 F01N009/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 25, 2008 |
FR |
0855119 |
Claims
1. A method for regulating the temperature of a particle filter in
an exhaust line of an engine during a regeneration phase of the
particle filter, by injecting fuel into exhaust gas flowing through
the exhaust line, comprising the steps of: measuring the
temperature at the particle filter; determining a quantity of fuel
to be injected in the exhaust gas (Qigec), the quantity including a
first component (Qc1c) determined through the intermediary of an
open control loop not taking into account the measured temperature,
and a second component (Qc2) determined through the intermediary of
a closed control loop taking into account the measured temperature;
calculating a correction factor (Kc) of the first component as a
function of the amplitude of the second component in comparison
with the calculated quantity of fuel, and applying the correction
factor in the open control loop.
2. The method according to claim 1, further comprising the steps of
calculating an indicator (I) representative of the amplitude of the
second component (Qc2) in comparison with the quantity of injected
fuel (Q.sub.igec), and applying the correction factor of the first
component in the open control loop when the indicator exceeds a
predetermined threshold (S).
3. The method according to claim 2, wherein said threshold (S) is
calculated as a function of at least one operating parameter of the
engine.
4. The method according to claim 2, wherein the correction factor
(Kc) of the first component is only applied in the open control
loop when several successive calculated values of the indicator (I)
exceed said threshold (S).
5. The method according to claim 2, wherein the indicator I is
calculated with the following equation: I = .intg. RG ( Qc 2 Qc 2 +
Q IGEC - Qc 2 ini Qc 2 ini + Q IGEC ini ) t .intg. RG t
##EQU00003## where RG is the regeneration time, Qc2.sub.ini and Qc2
are the flow values of the second component calculated respectively
at the a reference time and during the calculation in progress, and
Qigec.sub.ini and Qigec are the flow values of the fuel quantity to
be injected in the exhaust gas calculated respectively at the
reference time and during the calculation in progress.
6. The method according to claim 1, further comprising the step of
determining an exhaust gas flow and an exhaust gas temperature
upstream of an oxidizing catalyst installed upstream of the
particle filter, wherein the open loop control is based on a model
estimating the temperature at the particle filter as a function of
the exhaust gas flow, the exhaust gas temperature, and as a
function of the quantity of fuel to be injected (Qigec) in the
exhaust gas.
7. The method according to claim 1, further comprising the steps of
detecting an engine dysfunction and maintaining the applied
correction factor when the dysfunction is detected.
8. The method according to claim 1, wherein the closed control loop
comprises an integral proportional regulator.
9. An automotive vehicle equipped with an exhaust line comprising a
particle filter, a fuel injection device in the exhaust line
upstream of the particle filter; a measuring device for measuring
the temperature (T5) at the particle filter; a device for
calculating the quantity of fuel to be injected in the exhaust gas
in order to regulate the temperature (T5) at the particle filter,
including an open control loop not taking into account the measured
temperature and determining a first component of said fuel quantity
(Qc1c), and including a closed control loop taking into account the
measured temperature and determining the second component (Qc2) of
said fuel quantity; wherein the calculation device of the fuel
quantity to be injected determines a correction factor (Kc) of the
first component and application of this correction factor in the
open control loop in function of the amplitude of the second
component in comparison with the determined quantity of fuel to be
injected.
Description
[0001] The present invention claims the priority of French
application 0855119 filed on Jul. 25, 2008, the content of which
(text, drawings and claims) is incorporated here by reference.
[0002] The invention relates to particle filters, and in particular
methods for regulating the temperature of a particle filter
associated with a system of diesel fuel injection in the
exhaust.
[0003] A widely known technique for reducing the exhaust gas
particle content of a diesel engine consists in using a filter to
capture these particles as they exit the engine.
[0004] The particles accumulate in the filter and form soot, which
must be treated to avoid clogging of the filter. This treatment
takes place by raising the temperature of the filter in order to
burn the accumulated soot.
[0005] In order to implement this treatment in an optimum manner, a
first approach consists of adding an additive to the fuel in order
to lower the combustion temperature of the soot from 600.degree. C.
to 450.degree. C.
[0006] According to a second approach, diesel fuel is injected
directly into the exhaust gas. The combustion of this diesel fuel
inside an oxidizing catalyst upstream of the filter heats the
exhaust gas and brings the filter to the required temperature of
600.degree. C. This temperature must be regulated in order to keep
the temperature as stable as possible, and to ensure rapid and
effective regeneration.
[0007] The application with registration number FR07 57789 in name
of the applicant describes a method for regulating the temperature
at the entrance of the filter. This method associates an open loop
and a closed loop in order to regulate the temperature of the gas
at the entrance of the particle filter and to ensure combustion of
the soot. The open loop and the closed loop determine the
respective components of a quantity of fuel to be injected into the
exhaust. The quantity of fuel to be injected in the exhaust is
determined by accumulation of these components.
[0008] This type of regulation has however some inconveniences. In
practice, the exhaust elements to be regulated are subject to
aging, in particular the catalyst, the different temperature
probes, the air flow meter and the fuel injector. Leaks in the fuel
circuit can also occur. The production of the exhaust also leads to
dispersions. Since the thermal efficiency of the catalyst
deteriorates with aging, a larger quantity of fuel will have to be
injected into the exhaust to ensure regeneration. In normal
operation, the closed loop compensates this lack of fuel. Because
of the thermal energy of the exhaust circuit, the closed loop
correction produces its effects with a certain delay. To ensure
nevertheless that the temperature remains within the desired
temperature range, one solution can consist of lengthening the
regeneration phases, to the detriment of engine operation.
Otherwise, these variations of the regulation can result in too
high a temperature being applied at the entrance of the catalyst,
which can lead to its destruction.
[0009] The goal of the invention is to resolve one or more of these
inconveniences. The invention relates also to a method for adapting
the temperature regulation of a particle filter in an exhaust line
during a regeneration phase of this filter, by injecting fuel into
the exhaust gas, comprising the steps consisting of measuring the
temperature of the particle filter, determining the quantity of
fuel to be injected into the exhaust gas, this quantity comprising
a first component determined through the intermediary of an open
control loop not taking into account the measured temperature, and
this quantity comprising a second component determined through the
intermediary of a closed control loop taking into account the
measured temperature and, as a function of the amplitude of the
second component in comparison with the determined quantity of
fuel, determining a corrective factor for the first component and
applying this corrective factor in the open control loop.
[0010] According to a variant, the method comprises the calculation
of an indicator representing the amplitude of the second component
in comparison with the quantity of injected fuel, and application
of the correction factor of the first component in the open control
loop when the indicator exceeds a predetermined threshold.
[0011] According to another variant, the threshold is calculated as
a function of at least one operating parameter of the engine.
[0012] According to another variant, the correction factor of the
first component is only applied in the open control loop when
several successively calculated values of the indicator exceed said
threshold.
[0013] According to another variant, said indicator I is calculated
with the following equation:
I .quadrature. .intg. RG ( Qc 2 Qc 2 .quadrature. Q IGEC
.quadrature. Qc 2 ini Qc 2 ini .quadrature. Q IGEC ini ) t .intg.
RG t ##EQU00001##
where RG is the regeneration time, Q.sub.c2ini and Q.sub.c2 are the
flow values of the second component calculated respectively at a
reference time and during the calculation in progress,
Q.sub.igecini and Q.sub.igec are the flow values of the quantity of
fuel to be injected in the exhaust gas calculated respectively at a
reference time and during the calculation in progress.
[0014] According to another variant, the open control loop is based
on a model estimating the temperature at the particle filter as a
function of the exhaust gas flow, the exhaust gas temperature
upstream of the oxidizing catalyst which is installed upstream of
the particle filter, and as a function of the quantity of fuel to
be injected into the exhaust gas.
[0015] According to a variant, the method comprises the detection
of an engine dysfunction and maintenance of the applied correction
factor when a dysfunction is detected.
[0016] According to another variant, the closed control loop
comprises an integral proportional regulator.
[0017] The invention relates also to an automotive vehicle equipped
with an exhaust line comprising a particle filter, comprising a
fuel injection device in the exhaust line upstream of the particle
filter; a device for measuring the temperature at the particle
filter; and a device for determining the quantity of fuel to be
injected into the exhaust gas in order to regulate the temperature
of the particle filter, and comprising an open control loop that
does not take into account the measured temperature and calculating
a first component of said fuel quantity, and comprising a closed
control loop that takes into account the measured temperature and
calculating a second component of said fuel quantity.
[0018] The device for determining the quantity of fuel to be
injected calculates a correction factor for the first component and
applies this correction factor in the open control loop as a
function of the amplitude of the second component in comparison
with the calculated quantity of fuel to be injected.
[0019] Other characteristics and advantages of the invention will
become clear from the following description, provided as
non-limiting example, with reference to the attached drawings, in
which:
[0020] FIG. 1 illustrates schematically an exhaust line in which
the invention is implemented;
[0021] FIG. 2 illustrates an example of the method for regulating
the regeneration temperature of the particle filter;
[0022] FIG. 3 illustrates schematically the method for applying a
correction factor to the amplitude of the open loop.
[0023] The invention proposes to modify the respective amplitudes
of the two components of a quantity of fuel to be injected into the
exhaust. The amplitude of a component determined by a closed
control loop taking into account the temperature of the particle
filter is modified as a function of a component determined by an
open control loop not taking into account this temperature.
[0024] FIG. 1 illustrates a diesel engine 9 comprising an exhaust
line 1. The exhaust line 1 comprises an exhaust collector 2. The
exhaust gas passes through collector 2 at a temperature T4,
measured by temperature probe 7, and has a flow Qair, typically
measured by a flow meter (not shown). The exhaust line comprises a
diesel fuel injector 3. Injector 3 is installed upstream of an
oxidizing catalyst 4. Catalyst 4 is installed upstream of a
particle filter 5. During regeneration, the temperature T5 of the
air entering particle filter 5 must be maintained at approximately
600.degree. C. to allow for the combustion of soot formed by the
captured particles. To this end, diesel fuel is injected into the
exhaust through the intermediary of injector 3. The injected fuel
is oxidized by catalyst 4 during an exothermic reaction. A
temperature probe 6 measures the temperature at the particle filter
5, typically in a junction conduit between the oxidizing catalyst 4
and the particle filter 5.
[0025] A control device 8 illustrated in FIG. 2 commands the fuel
injections by injector 3 in order to regulate the temperature T5 at
the particle filter 5 during a regeneration. The temperature probe
6 measures the exhaust gas temperature T5 at the entrance of
particle filter 5. This temperature T5 must not be too high--which
would provoke deterioration or premature aging of filter and
catalyst--nor too low--which would stop soot combustion and
increase the overall regeneration time of the filter. The air
temperature T5 at the entrance of filter 5 is known thanks to probe
6. The target temperature to be achieved varies based on the
location of this probe 6, because the temperature inside filter 5
is higher than at its periphery.
[0026] Control device 8 determines a quantity of fuel to be
injected into the exhaust gas. This quantity is determined in the
form of a fuel flow command Q.sub.igec of injector 3 during an
injection time. A flow command associated with an injection time
constitutes in this way a fuel quantity command. The flow of fuel
to be injected is determined by two components, Qc1c and Qc2. The
sum of these two components is equivalent to the value of the flow
command Q.sub.igec.
[0027] The first component Qc1c is determined through the
intermediary of an open control loop. This open control loop does
not take into account temperature T5 measured by probe 6. The open
control loop is intended to have a rapid response time.
Advantageously, the open control loop is intended to define more
than 85 to 90% of the amplitude of the calculated fuel quantity to
be injected.
[0028] The open control loop uses for instance a thermal behavior
model of catalyst 4, as a function of the flow of the diesel fuel
injector Q.sub.igec, the exhaust gas temperature T4 and the exhaust
gas flow upstream of catalyst 4. A calculation module 83 is used
for this purpose, which exploits the thermal behavior model of
catalyst 4 to calculate an estimate of the temperature T5 at
particle filter 5.
[0029] The thermal behavior of catalyst 4 depends on rapid
regulation parameters such as the air flow in collector 2 of the
exhaust line 1. In fact, homogenization of the temperatures in this
line 1 occurs more rapidly with higher air flow. A second rapid
regulation parameter is the temperature T4 of the exhaust gas at
the entrance 2 of the exhaust line 1. A significant increase of
this temperature T4 generated by engine 9 results in an increase of
the temperature at the entrance of catalyst 4. Analogously, this
temperature rise at the entrance of the catalyst causes a rise of
the temperature T5 of filter 5--minus the heat loss to the
exterior. Besides these rapid regulation parameters, there are slow
regulation parameters of the filter temperature which the heat
propagation characteristics inside the catalyst influence the
temperature T5 at the filter.
[0030] The know-how of the technology indicates that, in a first
approximation, the hydrocarbon concentration inside catalyst 4
generates the rise of the temperature T5. This concentration is
defined by the relationship between fuel flow and air flow and can
be taken into account in the model.
[0031] The calculation module 83 issues a flow command Qc1 as a
function of this model.
[0032] The second component Qc2 is determined through the
intermediary of a closed control loop. The closed control loop
takes into account the temperature T5 measured by probe 6. This
temperature T5 is compared to a temperature command Ct. The
temperature command Ct is for instance 600.degree. C. The
difference between T5 and Ct is applied at the entrance of an
integral proportional regulator 81. The regulator 81 determines the
second flow component Qc2 as a function of the error corresponding
with this difference. The regulator 81 determines the second
component Qc2 by taking into account a factor in proportion with
the difference and a factor integrating this difference. The
objective of the integral factor is to ensure that temperature T5
is as close as possible to temperature command Ct.
[0033] Control device 8 comprises a correction device 84. This
correction device 84 determines the amplitude of the second
component Qc2 in comparison with the fuel flow Q.sub.igec. As a
function of this amplitude, correction device 84 determines a
correction factor Kc to be applied to the first component. This
correction factor is then applied in the closed control loop.
Correction factor Kc is a multiplication factor for flow command
Qc1, so that Qc1c=Qc1*Kc. It can also be envisaged that the
correction factor is added to the command Qc1.
[0034] By correcting the amplitude of the first component generated
by the open loop, the temperature regulation at the particle filter
will not be affected by aging of the exhaust line components 1,
clogging of the fuel dosage element (for instance the metering pump
or the injector), drifting of temperature probes 6 and 7 or
drifting of the air flow meters. Indeed, the proportion of the
first component in the injected fuel quantity command must be
maintained, so that the aging of the components will not induce an
accrued preponderance of the second component calculated by the
closed loop. In this way, the regulation will not be affected by
increased delay of its correction and the duration of the
regeneration phase can be maintained. In addition, the risk of
destroying catalyst 4 due to transient excessive exhaust gas
temperature is also reduced because the amplitude of the second
component is limited by the correction of the first component.
[0035] The correction device 84 typically increases the value of
correction factor Kc when the amplitude of the second component Qc2
increases in comparison with the injected fuel quantity
Q.sub.igec.
[0036] To validate the application of correction factor Kc in the
first component Qc1c, device 84 calculates an indicator I
representative of the amplitude of the second component Qc2 in
comparison with the injected fuel quantity Q.sub.igec. The
calculated correction factor Kc is only applied when indicator I
exceeds a predetermined threshold. The calculated correction factor
Kc replaces then the value of the previously applied correction
factor. The threshold for validating the application of the new
correction factor Kc can be calculated as a function of the
operating parameters of the engine such as vehicle speed, engine
torque or engine speed. In this way, the adaptation conditions of
the first component will depend on the driving pattern of the
vehicle.
[0037] The untimely application of the new correction factor can be
avoided during transient operating conditions. To further reduce
the risk of untimely change in correction factor, the condition can
be established that the indicator exceeds said threshold several
times in succession prior to validating the application of the new
calculated correction factor Kc. Indeed, since aging or drifting of
the components is a slow phenomenon, it is desirable that new
correction factors are not applied at too short intervals.
[0038] Advantageously, to avoid that an engine dysfunction, for
instance an internal or external fuel leak, would lead to erroneous
application of correction factor Kc, the application of the current
correction factor is maintained when such dysfunction is
detected.
[0039] The indicator I can be calculated with the following
equation:
I = .intg. RG ( Qc 2 Qc 2 + Q IGEC - Qc 2 ini Qc 2 ini + Q IGEC ini
) t .intg. RG t ##EQU00002##
where RG is the regeneration time, Qc2.sub.ini and Qc2 are the flow
values of the second component calculated respectively at a
reference time and during the last calculation, Qigec.sub.ini and
Qigec are the flow values of the fuel quantity to be injected into
the exhaust gas calculated respectively at a reference time and
during the last calculation. The reference time values can
correspond with previously stored values and can be read when the
vehicle starts. This indicator I is based on the integral part of
the closed control loop. The higher the indicator value, the poorer
the open control loop is regulated. The value of the correction
factor can be based on the indicator I.
[0040] As a general rule, the multiplication factor Kc is between
0.5 and 1.5 or .+-.50% of the nominal value. In practice, during
tests, the effective range is between 0.8 and 1.2.
[0041] FIG. 3 represents in schematic manner the method for
applying correction factor Kc of the first component. During step
101, indicator I is calculated as a function of values Qc2 and
Q.sub.igec. During step 102, threshold S is calculated as a
function of engine parameters such as vehicle speed or engine
torque. During step 103, indicator I is compared to threshold S. If
indicator I exceeds threshold S, then a validation signal is
generated for the correction factor. During step 104, correction
factor Kc is calculated as a function of indicator I. If a
validation signal of the correction factor is generated, the
correction factor Kc is applied to correct the first component.
[0042] The calculation of the correction factor and the validation
of its application can take place at the end of each regeneration.
If the new correction factor is valid, this factor can be updated
and applied for the following regeneration(s) of the particle
filter. The correction factor can be stored in the non-volatile
memory of control device 8. The correction factor can be updated as
soon as necessary, in particular when the catalyst is replaced.
When the catalyst is replaced by a new catalyst, the correction
factor must be modified in order to avoid overconsumption or
excessively high exhaust temperature.
[0043] Advantageously, a device 82 modifies the flow command of the
diesel injector in function of significant saturations of the
richness of the gas in the exhaust line 1. The fuel flow command
can be saturated before being submitted to injector 3. A more
precise regulation is obtained by taking into consideration the
saturations in the open control loop.
[0044] These saturations are derived mainly from the estimated
oxygen concentration in the exhaust line 1. In fact, the quantity
of fuel injected into the exhaust is limited by the reduction
capability of catalyst 4, which depends on the available quantity
of oxygen.
* * * * *