DE102006033929A1 - Method for adapting the metering of a reagent to be introduced into an exhaust region of an internal combustion engine and device for carrying out the method - Google Patents

Abstract

Proposed are a method for adapting the metering of a reagent to be introduced into an exhaust area (13) of an internal combustion engine (10) for the exothermic reaction on a catalytically active surface (16) and an apparatus for carrying out the method.
A precontrol (32) provides a controlled reagent metering signal (ste_s_DV) based on a functional relationship (33) at least as a function of a setpoint temperature (te_Sol). Furthermore, a controller (40) which compares the setpoint temperature (te_Sol) with the temperature (te_Abg_nK) measured downstream of the catalytically active surface (16) provides a regulated reagent dosing signal (ger_s_DV) to eliminate a detected temperature difference (d_te). It is intended to determine a time average (mit1) of a measure (d_te, ger_s_DV) for the control deviation, wherein the time for averaging is longer than the system dynamics. In the case of a non-zero mean value (with1), an adaptation signal (s_DV_Adap) for adapting the functional relationship (33) is provided. The procedure according to the invention makes it possible in particular to adapt a long-term drift which can occur during the metering of the reagent.

Description

State of the art

The The invention relates to a method for adapting the dosage of a in a waste gas region of an internal combustion engine to be introduced reagent for the exothermic reaction on a catalytically active surface and a device for carrying out of the procedure. The subject of the present invention is also a computer program and a computer program product.

In the DE 10 2005 041 660 A1 (not prepublished) a method for introducing a reagent into an exhaust region of an internal combustion engine is described in which a standing under a reagent pressure reagent is metered by a reagent metering device in response to a reagent signal. The pressure difference between the reagent pressure and the exhaust gas pressure is determined. The reagent signal is then influenced as a function of the pressure difference. As a result, the pressure difference in the dosage can be taken into account and used to correct the reagent signal, so that under- or over-dosing of the reagent can be avoided. As a reagent, a urea-water solution is provided, which is needed in an SCR catalyst as a reagent. The urea-water solution is sprayed directly into the exhaust gas area.

In the DE 10 2004 056 412 A1 a method for operating an internal combustion engine is described, in the exhaust gas region of which an exhaust gas treatment device is arranged and in which a reagent is introduced into the exhaust gas region of the internal combustion engine. The reagent agent pressure, which is in the reagent path between a reagent metering valve and a reagent delivery check valve, is detected during different states of the reagent safety valve and / or the reagent metering valve and compared to at least one threshold. If the threshold is exceeded, an error signal is provided. As a reagent, for example, fuel is provided, which is to react exothermically on a catalytically active surface in order to increase the temperature of the catalytically active surface or in particular of the exhaust gas for heating the exhaust gas treatment device.

In the DE 100 56 016 A1 a method for operating a particulate filter is described in which also fuel is introduced into the exhaust gas region of the internal combustion engine, which is to react exothermally to heat the particulate filter in the exhaust gas region. The introduction of the fuel is effected by at least one partial or non-combusting fuel post-injection in the cylinders of the internal combustion engine, which can be influenced by the crankshaft angle-related fuel injection time, the duration of the fuel injection and the fuel pressure.

Of the Invention is based on the object, the dosage of a reagent to optimize the exhaust gas range of an internal combustion engine.

The The object is achieved by those specified in the independent claims Features each solved.

Disclosure of the invention

The inventive approach allows an exact dosage of a reagent in the exhaust gas area of a Internal combustion engine based on an adaptation of one in one Precontrol stored functional relationship. The feedforward control represents a controlled reagent dosing signal based on the functional relationship at least in dependence ready from a given setpoint temperature. The functional context For example, a characteristic of a reagent metering valve or a map for a post-fuel injection into the internal combustion engine or a relationship between the setpoint temperature and the required Reflect the amount of reagent.

The inventive approach provides for this, that already the controlled reagent dosing signal is given comparatively precisely, so that a regulator which provides a regulated reagent dosing signal provides, at least in the steady state, little or even does not intervene. This stands for dynamic processes a large Control range available without that the regulated reagent dosing signal is technically conditioned saturation point reached.

advantageous Embodiments and developments of the procedure according to the invention arise from dependent Claims.

A Embodiment provides that as a measure of the deviation the difference between the set temperature and the measured temperature, which reflects the actual temperature used. An alternative Design provides that as a measure of the deviation from the Regulator provided regulated reagent dosing signal used becomes.

If a characteristic is assumed in the functional relationship, an offset error and a slope error can be adapted. At a small input of the functiona len relationship can be made an additive adaptation, which minimizes the offset error. With a large input of the functional relationship, a multiplicative adaptation can be made which minimizes the slope error.

The Averaging provided over a period longer than the system dynamics is. The settling time goes into the system dynamics of the regulator and the precontrol, the settling time of the reagent-introducing device, the Settling time of the sensors used, the duration of the exhaust gas in the exhaust gas area and the reaction time of the reagent on the catalytically active surface one.

The However, averaging is preferably performed only when the exhaust gas mass flow exceeds an exhaust mass flow threshold. Continue the averaging is preferably carried out only when the exhaust gas temperature upstream in front of the catalytically active surface exceeds a working temperature of the catalytically active surface, which is above the light-off temperature of the catalytically active surface, to the operational readiness of the catalytically active area Ensure insertion of the reagent.

A Design provides that in the provision of the controlled Dosageignals the exhaust gas mass flow and / or the exhaust gas temperature upstream considered the catalytically active area becomes. The exhaust gas mass flow can be determined from a suction area Air signal and one of the load of the internal combustion engine corresponding Fuel signal can be determined. The exhaust gas temperature upstream the catalytically active surface may be from the speed of the engine and the fuel signal be simulated.

The inventive device to carry out of the procedure concerns first a control unit, that to carry out the process is specially prepared.

The sees computer program according to the invention that all steps of the method according to the invention are carried out, when it runs on a computer.

The Computer program product according to the invention with a program code stored on a machine-readable carrier performs the method according to the invention off if the program is run on a computer or in the controller.

One embodiment The invention is illustrated in the drawing and in the following description explained in more detail.

The FIG. 1 shows a technical environment in which a method according to the invention expires.

The figure shows an internal combustion engine 10 , in their intake area 11 an air sensor 12 and in their exhaust area 13 a reagent delivery device 14 , a first temperature sensor 15 , a catalytically active area 16 , a second temperature sensor 17 and an exhaust gas purification device 18 are arranged.

The air sensor 12 represents a control unit 20 an air signal ms_L, the internal combustion engine 10 a speed n, the first temperature sensor 15 a first measured exhaust gas temperature te_Abg_vK_Mes and the second temperature sensor 17 a second measured exhaust gas temperature te_Abg_nK_Mes available.

The first temperature sensor 15 detects the upstream upstream of the catalytically active area 16 occurring exhaust gas temperature te_Abg_vK and the second temperature sensor 17 the downstream of the catalytically active area 16 occurring exhaust gas temperature te_Abg_nK. In the exhaust area 13 an exhaust gas mass flow ms_Abg occurs.

The reagent delivery device 14 is with a reagent dosing valve 21 connected, which is acted upon by a reagent dosing signal s_DV.

The control unit 20 represents a fuel metering device 22 a fuel signal m_K available.

The control unit 20 contains an exhaust gas mass flow determination 30 which determines a calculated exhaust gas temperature ms_Abg_Sim from the air signal ms_L and the fuel signal m_K. The control unit 20 also contains an exhaust gas temperature determination 31 which is a calculated upstream upstream of the catalytically active area 16 occurring calculated exhaust gas temperature te_Abg_vK_Sim from the speed n and the fuel signal m_K determined.

A feedforward control 32 determined from a for the exhaust gas purification device 18 predetermined setpoint temperature te_Sol, the exhaust gas mass flow ms_Abg and the exhaust gas temperature te_Abg_vK upstream of the catalytically active surface 16 a controlled reagent dosing signal ste_s_DV. The feedforward control 32 contains a functional context 33 that has a characteristic 34 and / or or a map containing, in the embodiment shown, the context between a desired reagent amount ms_HC and the controlled reagent dosing signal ste_s_DV.

A regulator 40 determined from the setpoint temperature te_Sol and the second measured exhaust gas temperature te_Abg_nK_Mes a regulated reagent dosing signal ger_s_DV, which in an adder 41 to the controlled reagent dosing signal ste_s_DV is added. The adder 41 provides the reagent dosing signal s_DV.

An average determination 50 determined from a temperature difference d_te or from the regulated reagent dosing signal ger_s_DV a mean mitl, which an adaptation signal determination 51 converted into an adaptation signal a_DV_Adap. The mean determination 50 continue to be the exhaust gas mass flow ms_Abg and the exhaust gas temperature te_Abg_vK upstream of the catalytically active area 16 made available.

The arrangement works as follows:

That in the exhaust area 13 reagent to be introduced is for the exothermic reaction on the catalytically active surface 16 provided, for example, the catalytically active area 16 itself or in particular the exhaust gas purification device 18 to heat.

The reagent may be used, for example, with the reagent delivery device 14 directly into the exhaust area 13 be sprayed. Additionally or alternatively, the reagent with incomplete combustion processes in the internal combustion engine 10 and / or completely separate post fuel injections into the internal combustion engine 10 to be provided. The inner engine provision of the reagent is carried out, for example, with the fuel signal m_K, which is the fuel delivery device 22 controls accordingly.

For targeted heating, for example, the exhaust gas purification device 18 , to the predetermined target temperature te_Sol is the knowledge of the exhaust gas mass flow ms_Abg appropriate, the exhaust gas mass flow determination 30 from, for example, the air signal ms_L determined and as a calculated exhaust gas mass flow ms_Abg_Sim provides. Optionally, the fuel signal m_K is additionally taken into account.

Furthermore, for a targeted heating of the exhaust gas cleaning device 18 to the given target temperature te_Sol the knowledge of the upstream of the catalytically active area 16 occurring exhaust gas temperature te_Abg_vK appropriate, which the exhaust gas temperature determination 31 as calculated exhaust gas temperature te_Abg_vK_Sim upstream of the catalytically active area 16 depending on, for example, the speed n and the fuel signal m_K.

The feedforward control 32 in particular, depending on the predetermined setpoint temperature te_Sol, for example 650 ° C, the controlled reagent dosing signal ste_s_DV ready. Optionally, the exhaust gas mass flow ms_Abg and / or the exhaust gas temperature te_Abg_vK upstream of the catalytically active area 16 considered. In particular from the setpoint temperature te_Sol and possibly the other variables, the feedforward control determines 32 the controlled reagent dosing signal ste_s_DV, which is required to increase the exhaust gas temperature with the exothermic reaction to the predetermined target temperature te_Sol.

The functional context 33 is in the embodiment shown by the characteristic 34 by way of example, which links the desired reagent quantity ms_HC to the controlled reagent metering signal ste_s_DV. As a functional context 33 can be provided, for example, the link between at least the predetermined setpoint temperature te_Sol and the reagent setpoint ms_HC

The characteristic 34 For example, corresponds to the characteristic of the reagent metering valve 21 or the required intervention in the fuel metering device 22 with the fuel signal m_K. It is essential that due to the functional context 33 the feedforward control 32 determines the controlled reagent dosing signal ste_s_DV as a function of at least the setpoint temperature te_Sol.

Depending on the accuracy of the functional relationship 33 the controlled reagent dosing signal ste_s_DV is provided correspondingly accurately, so that an intervention by the regulated reagent dosing signal ger_s_DV may not be necessary. However, if there are deviations, this is done by the regulation 40 an intervention with the regulated reagent dosing signal ger_s_DV. The unregulated and regulated reagent dosing signal ste_s_DV, ger_s_DV are in the adder 41 to the reagent dosing signal s_DV merged, which, for example, the metering valve 21 controls or which is used, for example, to influence the fuel signal m_K by a transformation not shown in detail.

The intervention by the regulated reagent dosing signal ger_s_DV takes place in particular in transient or transient processes of the Internal combustion engine 10 in which, for example, a change in the exhaust gas mass flow ms_Abg and / or, for example, a change in the exhaust gas temperature te_Abg_vK upstream of the kata lytisch effective area 16 occur. The regulated reagent dosing signal ger_s_DV has a predetermined, technically induced dynamics. In order to cover the possible control range as completely as possible in both the positive and in the negative direction, care should be taken that at least in stationary states of the internal combustion engine 10 the controlled reagent dosing signal ste_s_DV corresponds as closely as possible to the actually required reagent dosing signal s_DV.

The characteristic 34 is therefore suitably adapted in particular with regard to a long-term drift. The adaptation carries out the adaptation signal s_DV_Adap, which defines the adaptation signal 51 depending on the mean mitl provides, which the average value determination 50 determined as a function of either the temperature difference d_te or in dependence on the regulated reagent dosing signal s_DV_Adap.

The temperature difference d_te is the difference between the setpoint temperature te_Sol and the second measured exhaust gas temperature te_Abg_nK_Mes upstream of the catalytically active area 16 optionally, the already existing result of the exothermic reaction of the reagent on the catalytically active surface 16 reflects.

Instead of the difference between the setpoint temperature te_Sol and the second measured exhaust gas temperature te_Abg_nK_Mes can also be the manipulated variable of the controller 40 , So the regulated Reagenzmitte1 dosing signal ger_s_DV be subjected to the averaging.

The averaging time should be longer than the system dynamics. Under system dynamics, the settling times become, for example, the precontrol 32 , the regulator 40 , the running times of the exhaust gas in the exhaust gas area 13 , the settling time of the metering valve 21 or the reaction times of the fuel delivery device 22 and the settling time of the second temperature sensor 17 and optionally the first temperature sensor 15 Understood.

The time for averaging should therefore be dynamic processes in the exhaust area 13 hide a faulty adaptation of the functional context 33 due to short-term influences. The averaging is done in practice, for example, over a period of time that may be in the minute range.

In order to rule out a faulty adaptation, first of all the exhaust gas mass flow ms_Abg is considered. The averaging preferably takes place only when the exhaust gas mass flow ms_Abg exceeds a predetermined threshold value. Preferably, the averaging continues to take place only when the exhaust gas temperature te_Abg_vK upstream of the catalytically active surface 16 exceeds a minimum temperature, which is the lower limit of the working temperature range of the catalytically active area 16 equivalent. The working temperature range of the catalytically active surface 16 is for example in a range of 350 ° C - 400 ° C. This takes into account the required conversion of the reagent, so that the working temperature of the catalytically active surface 16 above the light-off temperature of, for example, 250 ° C of the catalytically active area 16 which applies to an exhaust gas without additionally introduced reagent.

A non-zero mean, mitl, which reflects deviations from the ideal state, should be brought to zero as far as possible with the adaptation. The term "zero" is to be understood to mean that the definition of the reagent dosing signal s_DV alone with the precontrol 32 without intervention of the regulator 40 could be done. From the deviation of the mean mitl from zero determines the adaptation signal setting 51 the adaptation signal s_DV_Adap, which is the functional relationship 33 in the feedforward control 32 adapted.

The adaptation of the characteristic 34 as an example of the functional relationship can be done, for example, that individual characteristic points are moved up or down. Optionally, a correction of whole areas may be provided.

According to one embodiment, it is provided that for a small input of the functional relationship 33 - In the illustrated embodiment, a small reagent setpoint ms_HC - an additive adaptation of the functional relationship 33 or the characteristic curve 34 is provided, which the entire characteristic 34 moves up or down. This becomes an offset error of the functional relationship or the characteristic 34 adapted. Accordingly, it can be provided that with a comparatively large input variable of the functional relationship 33 - In the illustrated embodiment, a large reagent setpoint ms_HC - a multiplicative adaptation of the functional relationship 33 or the entire characteristic curve 34 is made, which is the slope of the characteristic 34 changes.

In particular, a long-term drift of the metering valve can be achieved with the adaptation signal s_DV_Adap 21 and / or the fuel delivery device 22 be recognized and adapted. Furthermore, with the adaptation signal s_DV_Adap a change in the effectiveness of the catalytically active surface 16 be compensated. For this purpose, the desired reagent quantity ms_HC to be preset can be adapted, which likewise has a functional relationship (not shown in more detail) 33 at least in dependence on the predetermined setpoint temperature te_Sol in the feedforward control 32 is deposited.

As a result, an increase in the controlled reagent dosing signal ste_s_DV in this case also causes a long-term drift due to a decrease in the effect of the catalytically active surface 16 be compensated.

The catalytically active area 16 and the exhaust gas purification device 18 can both as separate components the exhaust area 13 as well as being realized as a single exhaust component. The exhaust gas purification device 18 is preferably a particle filter, which optionally additionally has a coating serving as the catalytically active surface 16 acts.

The second temperature sensor 17 is in the range of the catalytically active area 16 or downstream of the catalytically active area 16 to install.

Alternatively it can be provided that the second temperature sensor 17 a measure of the temperature of the exhaust gas purification device 18 detects which is to bring to the desired temperature te_Sol corresponding required operating temperature, such as a particulate filter regeneration operating temperature or a NOx storage catalyst desulfurization operating temperature.

Claims (13)

Method for adapting the metering of an into an exhaust area ( 13 ) an internal combustion engine ( 10 ) to be introduced reagent for exothermic reaction on a catalytically active surface ( 16 ), in which a pilot control ( 32 ) at least in dependence on a setpoint temperature (te_Sol) on the basis of a functional relationship ( 33 ) provides a controlled reagent dosing signal (ste_s_DV) in which a controller ( 40 ) compares the setpoint temperature (te_Sol) with the measured temperature (te_Abg_nK) and provides a controlled reagent dosing signal (ger_s_DV) for eliminating a detected temperature deviation (d_te), wherein a time average (mitl) of a measure (d_te, ger_s_DV) for the Control deviation is determined, wherein the time for the averaging is longer than the system dynamics and in which at a non-zero mean (mitl) an adaptation signal (s_DV_Adap) for adapting the functional relationship ( 33 ) provided. The method of claim 1, wherein as a measure of the control deviation the difference (d_te) between the set temperature (te_Sol) and the measured temperature (te_Abg_nK) is used. Method according to claim 1, in which as a measure of the control deviation the control ( 40 ) supplied regulated reagent dosing (ger_s_DV) is used. The method of claim 1, wherein at a low input (ms_HC) of the functional relationship ( 33 ) an additive adaptation of the functional relationship ( 33 ) is made. The method of claim 1, wherein at a high input (ms_HC) of the functional relationship ( 33 ) a multiplicative adaptation of the functional relationship ( 33 ) is made. The method of claim 1, wherein the averaging only performed when the exhaust mass flow (ms_Abg) exceeds an exhaust mass flow threshold. The method of claim 1, wherein the averaging is performed only when the exhaust gas temperature (te_Abg_vK) upstream of the catalytically active surface ( 16 ) a predetermined operating temperature of the catalytically active surface ( 16 ) exceeds. Method according to Claim 1, in which, when the controlled metering signal (ste_s_DV) is provided, the exhaust gas mass flow (ms_Abg) and / or the exhaust gas temperature (te_Abg_vK) upstream of the catalytically active surface ( 16 ). Method according to Claim 8, in which the exhaust gas temperature (te_Abg_vK) upstream of the catalytically active area ( 16 ) from the rotational speed (s) of the internal combustion engine ( 10 ) and a fuel signal (m_K) is calculated. The method of claim 8, wherein the exhaust gas mass flow (ms_Abg) from a in the intake ( 11 ) of the internal combustion engine ( 10 ) determined air signal (ms_L) and a fuel signal (m_K) is determined. Device for adapting the metering of one into an exhaust area ( 13 ) an internal combustion engine ( 10 ) to be introduced on a catalytically active surface ( 16 ) exothermic reaction, characterized in that at least one for carrying out the method according to one of claims 1 to 10 specially prepared control unit ( 20 ) is provided. Computer program that shows all the steps of a procedure according to one of the claims 1 to 10 executes, when it runs on a computer. Computer program product with a program code stored on a machine-readable carrier for carrying out the method according to one of Claims 1 to 10, when the program is stored on a computer or in the control unit ( 20 ) is performed.