DE102017201742A1 - Method for heating and regenerating a particulate filter in the exhaust gas of a gasoline engine - Google Patents

Abstract

A method for heating and regenerating a particulate filter (26) arranged in the exhaust gas flow of a gasoline engine (10) downstream of a catalytic converter (30) is provided with a device (50) for supplying secondary air to the exhaust gas flow between the catalytic converter (30) and the particulate filter (26 ). The method is characterized in that cross-sensitivities of a lambda probe arranged between the catalytic converter and the particle filter are compensated for oxygen components other than exhaust gas. Further independent claims are directed to a gasoline engine, a computer program product, and a computer-readable medium.

Description

State of the art

The present invention relates to a method for heating and regenerating a particulate filter arranged downstream of a catalytic converter in the exhaust gas stream of an Otto engine, the gasoline engine having a device for supplying secondary air to the exhaust gas stream between the catalytic converter and the particulate filter, according to the preamble of claim 1.

Moreover, the invention relates to a gasoline engine having such a device according to the preamble of claim 10, a computer program product and a computer-readable medium.

Such a method and such a gasoline engine are assumed to be known per se. In today's engine control systems lambda probes are used to detect the oxygen concentration in the exhaust gas and the lambda control of the gasoline engine. Broadband lambda probes and leaky lambda probes are used.

As a rule, broadband lambda probes are used where fat or lean lambda values are to be measured accurately, or where a measurement in the range around lambda = 1 is sufficient with limited accuracy. Broadband lambda probes allow lambda to be measured over a wide range of air frequencies. In the case of a lambda lambda probe, the signal changes abruptly at lambda = 1, so that small lambda changes there lead to large signal changes. Therefore, jump lambda probes are used where the exhaust lambda in the range around lambda = 1 should be measured with high accuracy. See Bosch, Automotive Handbook, 23rd Edition, page 524.

Typical applications for a broadband lambda probe are the lambda control, which is based on the pre-catalyst lambda sensor signal, and the oxygen input and output balancing in the catalyst diagnosis. Typical applications of a leaky lambda probe are the very accurate lambda = 1 control with a jump lambda probe arrangement behind a catalytic converter and the detection of the breakdown of rich or lean exhaust gas in the diagnosis of the catalytic converter.

A typical exhaust system of an Otto fuel-powered gasoline engine for today's stringent emission and on-board diagnostic requirements (eg, SULEV) includes a broadband lambda probe, a first three-way catalyst located downstream of this lambda probe, a stepping lambda probe located downstream of the first three-way catalyst and a second, unsupervised three-way catalyst disposed downstream thereof. Future even stricter emission and diagnostic requirements are likely to require exhaust systems that not only monitor the second catalyst, but also limit the number of particulates in the tail pipe emissions. The second three-way catalyst must therefore be combined with a particulate filter or replaced with a coated particulate filter, also referred to as a four-way catalyst.

To meet the future emission and diagnostic requirements in particular an exhaust system is in question in the exhaust gas flow of the gasoline engine, a first lambda probe (broadband) upstream of a three-way catalyst, a second lambda probe (broadband or jump) downstream of the three-way catalyst, a particulate filter, preferably a catalytic coated particulate filter, and a third lambda probe (jump), which is arranged downstream of the particulate filter having. Between the catalyst and the particulate filter, a secondary air supply is additionally provided, which can be carried out upstream or downstream of the second lambda probe. The signal of the second lambda probe should be used in this system, in particular for optimal operation of the preferably coated particulate filter. Optimum operation of the preferably coated particulate filter is characterized by rapid achievement of the operating temperature and rapid regeneration.

Optimum operation presupposes that there is a clear relationship between the lambda at the installation point of the second lambda probe and the signal of this second lambda probe, since otherwise the accuracy of a control of the air ratio lambda based on this signal is insufficient and unacceptably high emissions or damage of the particulate filter can occur. Since the signal of the second lambda probe is usually influenced by different sensitivities of the second lambda probe for oxygen and cross sensitivities of the second lambda probe to different exhaust gas components (eg CO, CO ₂ , H ₂ , H ₂ O, HC, NO _x ), and since the exhaust gas composition can differ despite the same Abgaslambda at different operating conditions, this condition is not met in both a broadband lambda probe as well as a jump lambda probe in the rule.

Disclosure of the invention

From the above-mentioned prior art, the present invention differs in its method aspects by the characterizing features of claim 1 and in their device aspects by the characterizing features of claim 10. With respect to the computer program product, the invention comprises the features of claim 11, and With respect to a computer program product, the invention comprises the features of claim 12.

With regard to the method aspects, it is accordingly provided that the gasoline engine and the device for supplying secondary air for heating the particulate filter are operated such that a first value of an air ratio lambda, which establishes a first excess of fuel in the exhaust gas, occurs at the output of the catalytic converter represents there prevailing exhaust gas atmosphere and at the entrance of the particulate filter on average a second value of the air ratio lambda corresponding to a stoichiometric composition of the prevailing exhaust gas atmosphere that the gasoline engine and the device for supplying secondary air for the regeneration of the particulate filter are controlled so that there are predetermined values of an air ratio lambda between the catalytic converter and the particulate filter; Output signals of a lambda probe arranged in the exhaust gas flow between the catalytic converter and the particulate filter and sensitive to oxygen as the exhaust gas component, a concentration of at least one further exhaust gas constituent is determined, and the values of the air ratio lambda depend on the detected output signals and additionally in dependence on the concentration of the at least one further exhaust gas constituent determined and taken into account in controlling the gasoline engine and / or the device.

As a result of these features, a signal of a lambda probe also installed between the first catalytic converter and the coated catalytic converter is provided for an exhaust system with secondary air supply between a first catalytic converter and a coated particle filter, which permits optimal operation of the particle filter independently of the exhaust gas composition.

The inventive correction of the output signal of the arranged between the catalyst and the coated particulate filter lambda probe such that regardless of the current exhaust gas composition results in a clear relationship between the probe signal and the exhaust lambda at the probe position, in particular the coated particulate filter with respect to a quick achievement its operating temperature and in relation to a regeneration required from time to time to be operated optimally, in particular with active secondary air supply.

A preferred embodiment is characterized in that the gasoline engine and the device for supplying secondary air for heating the particulate filter are operated so that a third value of a lambda air value, which has a stoichiometric value or a second one, is established at the output of the catalyst over the time average Represents excess fuel in the prevailing exhaust gas atmosphere there, which is at least smaller than the first excess fuel, and at the entrance of the particulate filter, a fourth value of the air ratio lambda sets, which corresponds to an excess of air in the prevailing exhaust gas atmosphere, output signals in the exhaust gas flow between the catalyst and the Particle filter arranged and sensitive for oxygen as an exhaust gas constituent lambda probe are detected, a concentration of at least one further exhaust gas constituent is determined, and that the determination of the air ratio lambda in dependence on the detected Ausgan gssignalen and in addition depending on the concentration of at least one further exhaust gas component. The determination preferably takes place in such a way that an influence of the concentration of the further exhaust gas constituent on the output signal of the lambda probe is corrected in determining the air ratio lambda, i. is at least partially eliminated.

A further preferred refinement is characterized in that the concentration of the at least one further exhaust gas component is modeled from measured variables available in a control unit of the gasoline engine.

By taking into account the concentration of the at least one further exhaust gas constituent at the probe position, the accuracy of the lambda value determined from the output signal of the lambda probe is increased. The quality of the lambda control and other functions, in particular for heating and regenerating the particulate filter, which are based on the measured lambda of the second lambda probe, is improved. Pollutant emissions are reduced and damage to the particulate filter due to overheating is prevented.

The method is applicable to both a broadband lambda probe and a lower cost lambda lambda probe between the two catalysts.

For exhaust systems of the aforementioned type, in which a secondary air supply takes place downstream of the second lambda probe in front of the coated particle filter, it is preferred that the first value and the third value be changed a combustion chamber lambda of the gasoline engine is set.

For these exhaust systems, it is further preferred that the second value and the fourth value be adjusted by changes in the supply of secondary air to the exhaust gas flow.

For these exhaust systems, it is also preferred that concentrations of hydrogen and of carbon monoxide are determined as concentrations of further exhaust gas constituents and that a time-varying ratio of the concentration of hydrogen to the concentration of carbon monoxide at rich lambda at the outlet of the catalyst and different cross-sensitivities of the lambda probe for hydrogen and carbon monoxide be taken into account. (Effect 1).

For exhaust systems of the type mentioned in the introduction, in which a secondary air supply takes place upstream of the second lambda probe and downstream of the first catalyst, it is preferred that the first value and the third value in a supply of secondary air between the catalyst and the lambda probe by coordinated adjustment of the combustion chamber lambda and the secondary air supply.

For these exhaust systems, it is further preferred that the second value and the fourth value be adjusted by changes in the supply of secondary air to the exhaust gas flow.

For these exhaust systems, it is further preferred that concentrations of hydrogen and of carbon monoxide are determined as concentrations of further exhaust gas constituents and that a time-varying ratio of the concentration of hydrogen to the concentration of carbon monoxide at rich lambda at the outlet of the catalyst and the different cross-sensitivities of the lambda probe for hydrogen and Carbon monoxide are taken into account. (Effect 1), and that in addition a cross-sensitivity of the lambda probe for oxygen and a taking place in the lambda probe pre-catalysis of hydrogen with oxygen is taken into account. (Effect 2).

Further advantages will become apparent from the description and the accompanying figures.

It is understood that the features mentioned above and those yet to be explained below can be used not only in the particular combination given, but also in other combinations or in isolation, without departing from the scope of the present invention.

• 1 einen Ottomotor mit einer ersten Abgasanlage;
• 2 einen Ottomotor mit einer zweiten Abgasanlage; und
• 3 ein Flussdiagramm als Ausführungsbeispiel des erfindungsgemäßen Verfahrens

Embodiments of the invention are illustrated in the drawings and are explained in more detail in the following description. In this case, the same reference numerals in different figures denote the same or at least functionally comparable elements. In each case, in schematic form:

• 1 a gasoline engine with a first exhaust system;
• 2 a gasoline engine with a second exhaust system; and
• 3 a flowchart as an embodiment of the method according to the invention

In detail, the shows 1 a gasoline engine 10 with an air supply system 12, a first exhaust system 14.1 and a controller 16 , In the air supply system 12 there is an air mass meter 18 and a downstream of the air mass meter 18 arranged throttle 19 , The over the air supply system 12 in the gasoline engine 10 flowing air is in combustion chambers 20 of the gasoline engine 10 blended with gasoline, via injectors 22 directly into the combustion chambers 20 or injected in front of intake valves of the combustion chambers. The resulting combustion chamber fillings are ignited 24 For example, spark plugs, ignited and burned. A rotation angle sensor 25 detects the angle of rotation of a shaft of the gasoline engine 10 and allowed the controller 16 thereby triggering the ignitions in predetermined angular positions of the shaft. A driver's desire 38 detects an accelerator pedal position and thus torque requirements of the driver and passes torque request signals to the controller 16 ,

The control unit 16 forms from the input signals, which include other than the only mentioned as an example signals, drive signals for actuators of the gasoline engine, which among other things cause the gasoline engine generates the required torque. The resulting from the burn exhaust gas is through the first exhaust system 14.1 derived. The control unit 16 has a computer readable medium 16.1 , For example, a memory chip on which an inventive, ie the instructions of the claim 10 comprising computer program product 16.2 stored in machine readable form.

The first exhaust system 14.1 has a three-way catalyst 30 and one downstream of the three-way catalyst 30 arranged in the exhaust stream gasoline particulate filter 26 on. The gasoline particle filter 26 has an inner honeycomb structure made of porous filter material, which is from the exhaust gas 28 is flowed through and in the exhaust 28 Retains contained particles.

The particulate filter is based, for example, on a particulate filter whose filter material is catalytically coated so that in addition to its particulate filter effect it still has the effect of a three-way catalyst. The three-way catalyst is known to convert the three exhaust gas constituents nitrogen oxides, hydrocarbons and carbon monoxide into three reaction paths. The particulate filter action represents a fourth way, which is the designation as a four-way catalyst. If a particulate filter is mentioned below, it means both particulate filters with catalytic coating of the filter material and particulate filters without such a coating.

The loading of the particle filter 26 with particles increases its flow resistance for the exhaust gas 28 and thus one above the gasoline particulate filter 26 adjusting differential pressure. The differential pressure is for example with a differential pressure sensor 29 measured, whose output signal is transferred to the control unit, or it is calculated from the information present in the control unit (measured values and / or manipulated variables) with a calculation model. From the in the control unit 16 known exhaust gas mass flow and the differential pressure results in the flow resistance by calculation or characteristic access. Upstream of the three-way catalyst 30 is a front lambda probe exposed to the exhaust gas 32 immediately before the three-way catalyst 30 arranged. Downstream of the particulate filter 26 is a rear lambda probe also exposed to the exhaust gas 34 immediately after the particle filter 26 arranged. The front lambda probe 32 is preferably a broadband lambda probe, which allows a measurement of the air ratio lambda over a wide Luftzahlbereich away. The rear lambdasonde 34 is preferably a so-called jump lambda probe, with which the air ratio lambda = 1 can be measured very accurately, because the signal of this lambda probe changes abruptly there. See Bosch, Automotive Handbook, 23rd Edition, page 524 ,

One from the control unit 16 controlled device 50 for the supply of secondary air, for example a secondary air pump, is arranged and arranged, air between the catalyst 30 and the particulate filter 26 in the first exhaust system 14.1 to blow in enough oxygen for a quick heating of the particulate filter 26 on its operational readiness (for example, to the light off temperature of a catalytic coating) and to provide effective regeneration of the particulate filter, without the gasoline engine for one with the pollutant conversion in the first catalyst 30 unfavorable excess air must be operated.

The control unit 16 processes the signals of the air mass meter 18 , the angle of rotation sensor 25 , the differential pressure sensor 29 , the front lambda probe 32 , the rear lambda probe 34 and an optional existing, a temperature of the particulate filter detecting temperature sensor 36 and forms therefrom drive signals for adjusting the angular position of the throttle valve 18 , for triggering ignitions by the ignition device 20 for injecting fuel through the injectors 22 and for controlling the secondary air pump 50 , Alternatively or additionally, the control unit processes 16 Also signals from other or other sensors for controlling the illustrated actuators or other or other actuators.

2 shows the device from the 1 with a second exhaust system 14.2. The two exhaust systems 14.1 and 14.2 differ in that the second lambda probe 34 in the case of the first exhaust system 14.1 upstream of a junction 52 a secondary air supply is arranged, and in the case of the second exhaust system downstream of a junction 52 a secondary air supply. Incidentally, the two exhaust systems 14.1 and 14.2 identical. The description of 1 applies in this respect also for the 2 , Both exhaust systems have in common that the secondary air supply downstream of the catalyst 30 and upstream of the particulate filter 26 he follows.

For faster heating of the particle filter 26 at its operating temperature is in the case of a rich combustion chamber mixture by secondary air supply in front of the particle filter 26 an exothermic reaction in the preferably coated particulate filter 26 caused. In order to avoid unnecessary emissions, it must be in front of the particulate filter 26 a medium exhaust lambda of 1 are kept as accurately as possible.

At a sufficiently high temperature of the particulate filter 26 By excess oxygen burns the soot loading and thus the regeneration of the particulate filter 26 to reach. For this purpose, a defined lean lambda must be maintained before the particle filter 26. At the same time the best possible conversion in the catalyst 30 ensure a combustion lambda of 1 is set during regeneration.

For heating the particle filter 26 should be downstream of the catalyst 30 set a rich exhaust gas atmosphere, for example, a lambda value of 0.9. At the same time should be at the entrance of the particulate filter 26 give a stoichiometric (lambda = 1) composite exhaust atmosphere.

For a regeneration of the particle filter 26 should be immediately downstream of the catalyst 30 yield a stoichiometrically composed (lambda = 1) or slightly rich (eg lambda = 0.99) exhaust gas atmosphere. At the same time should be on Input of the particle filter 26 give a lean (eg lambda = 1.1) composite exhaust atmosphere.

Depending on whether the secondary air supply downstream of the second lambda probe 34 (first exhaust system, 1 ) or upstream of the second lambda probe 34 (second exhaust system, 2 ) is arranged, meets the second. lambda probe 34 various tasks:

In the first exhaust system with the second lambda probe, the desired lambda downstream of the catalyst 30 regulated with a closed loop. The control adjusts the combustion chamber lambda accordingly. The secondary air pump 50 is from the controller 16 controlled in an open timing chain so that in front of the preferably coated particulate filter 26 sets the stoichiometric exhaust gas composition (lambda = 1). In the second exhaust system is with the second lambda probe 34 the desired lambda immediately upstream of the coated particulate filter 26 adjusted in a closed loop. The control adjusts both the combustion chamber lambda and the secondary air supply accordingly.

The respective task to specify the oxygen concentration exactly, the second lambda probe 34 only sufficiently accurate fulfill, if between the location of the second lambda probe 34 prevailing Lambdaistwert and the signal of this lambda probe 34 there is a clear connection. This is usually not the case. Depending on the exhaust gas composition at the installation location of the second lambda probe 34 this can, despite the same lambda actual value, have different output signals.

By way of example, two effects which may be considered as possible causes are described below:

effect 1 : Behind a three-way catalytic converter, a time-varying ratio between hydrogen H ₂ and carbon monoxide CO arises at a constant rich lambda. The reason for this is the water gas shift reaction, in which water resulting from HC and O ₂ in the exhaust gas reacts with CO to form H ₂ and CO ₂ , and the catalyst can not (permanently) set the reaction equilibrium. After a change from lambda = 1 or a lean lambda to a constant rich lambda, the catalyst first supplies an amount of H ₂ which corresponds approximately to the reaction equilibrium. Over time, however, the first catalyst delivers significantly too much CO compared to H ₂ . Because of the different cross sensitivities for H ₂ and CO, the lambda probe downstream of the three-way catalytic converter consequently also shows a time-varying signal when the lambda actual value at the installation location of the second lambda probe is constant.

effect 2 When the secondary air supply is active, the different cross-sensitivities of the lambda probe for H ₂ , CO and O _{2 are followed by} a pre-catalysis of H ₂ with O ₂ in the probe. Because only small amounts of the existing O _{2 can be} catalytically reacted in the probe, this proportion is highly dependent on the amount of O ₂ present. Here too, depending on the exhaust gas composition, a different probe signal sets in than would result for the same oxygen concentration without the influences of the other exhaust gas constituents. Such cross-sensitivities of lambda probes mean that the output signal is not only dependent on the oxygen concentration but also on the concentrations of other exhaust gas constituents.

The invention provides for these and similar effects to be taken into account and the output between the catalyst 30 and the preferably coated particulate filter 26 built-in second lambda probe 34 Correct accordingly. In particular, it is provided, the current exhaust gas composition, or the concentration of individual relevant exhaust gas components at the position of the second lambda probe 34 and to model their cross sensitivity to these exhaust gas components based on variables available in the control unit and to correct the output signal of the lambda probe accordingly.

In the case of the first exhaust system downstream of the second lambda probe 34 secondary air supply is preferably provided, the time-varying H ₂ / CO ratio at rich or slightly rich lambda behind the catalyst 30 and to consider the different cross-sensitivities of the second lambda probe for H ₂ and CO than to consider a first effect.

In the case of the exhaust system with the secondary air supply before the second lambda probe 34 is preferably provided, in addition to the first effect as a second effect to take into account a sensitivity of the lambda probe for O ₂ and the pre-catalysis of H ₂ with O ₂ in the second lambda probe.

3 shows a flowchart as an embodiment of a method according to the invention, or computer program product 16.2 , The block 100 represents a main program for controlling the gasoline engine 10 in which the control unit 16 in particular determines the manipulated variables with which the gasoline engine 10 generates the required torque.

For this main program 100 out is repeated a step or subprogram 102 achieved in which the control unit 16 read in the signals of the connected sensors. In the step 102 in particular, the output signal of the second lambda probe 34 read. This signal serves as base value for the determination of the different air value values.

In step 104 determines the control unit 16 a concentration of at least one further exhaust gas constituent and determines the air ratio lambda as a function of the output signal of the second lambda probe 34 and additionally depending on the concentration of the further exhaust gas constituent. In this case, concentrations of hydrogen and carbon monoxide are preferably determined as concentrations of further exhaust gas constituents, and a time-varying ratio of the concentration of hydrogen to the concentration of carbon monoxide at rich lambda at the outlet of the catalyst (ie lambda 1 or lambda 3 ) and different cross-sensitivities of the lambda probe for hydrogen and carbon monoxide are taken into account. (first effect).

It is also preferred that concentrations of hydrogen and carbon monoxide are determined as concentrations of further exhaust gas constituents and that a time-varying ratio of the concentration of hydrogen to the concentration of carbon monoxide at rich lambda at the outlet of the catalyst and the different cross-sensitivities of the lambda probe for hydrogen and carbon monoxide are taken into account , (Effect 1 ), and that in addition a sensitivity of the lambda probe for oxygen and a taking place in the lambda probe Vorkatalyse of hydrogen with oxygen is taken into account. (second effect).

The determination takes place, for example, according to one of DE 10 2012 221 549 A1 or one from the DE 10 2006 011 894 A1 known methods. In the from the DE 10 2012 221 549 A1 known method, a concentration of a further exhaust gas component such as carbon monoxide, carbon dioxide, hydrogen, hydrocarbons or nitrogen oxide from the control unit from a computer model is determined or determined on the basis of available in the control unit parameters. Subsequently, a conversion of the output signal of the lambda probe into a lambda value by means of a reference characteristic of the exhaust gas sensor.

In the from the DE 10 2006 011 894 A1 For a determination of a concentration of hydrogen as a further exhaust gas component known method is initially when the output signal of the oxygen-sensitive lambda probe of a stoichiometric exhaust gas composition corresponds, the said output signal time differentiated. The differentiated output is compared to a lower threshold. An occurrence of hydrogen in the exhaust gas is detected when the time-differentiated output signal exceeds the lower threshold. It is therefore assumed that the influences of the other exhaust components lead to rapid changes of the not yet differentiated output signal and thus to relatively large values of the time derivative of the output signal. The lower threshold exceeding portions of the differentiated output signal are integrated. The integral thus depicts the influence of the other exhaust gas components on the output signal. In order to compensate for this influence, a correction signal obtained by the integration is subtracted from the output signal.

Accordingly, the consideration takes place in that an output signal of the lambda probe is corrected with a correction which depends on the composition of the gas mixture.

As a result of the correction, the influence of the further exhaust gas constituent element which falsifies the output signal of the lambda probe is eliminated at least in part, so that the corrected output signal indicates the true oxygen concentration more accurately than the uncorrected output signal of the lambda probe.

The corrected output signal is then processed further as an output signal corrected with respect to a hydrogen cross-sensitivity of the lambda probe, wherein the further processing takes place, for example, for the purpose of a lambda control.

A lambda control based on the output signal of the lambda probe becomes particularly accurate and reliable by taking into account the cross sensitivities in the various engine operating points. Inadmissibly high emissions of unwanted exhaust gas components can thus be avoided.

In step 106 it is checked whether a regeneration of the coated particulate filter should be started or whether an already started regeneration should be continued. If this is not the case, the procedure goes to step 114 in which it is checked whether the temperature of the preferably coated particulate filter 26 greater than a minimum temperature required for its operational readiness. If this is the case, in step 115 a possibly still activated heating of the particulate filter is deactivated, and the procedure with the main program in the block 100 continued. On the other hand, if the temperature is too low, it will become out of step 114 out in the step 116 branches, in which a heating of the preferably coated particulate filter 26 triggered or maintained. The heating system is preferably done with the support of the secondary air supply. The heating is aborted during the repeated process run, if necessary, by negating the query in step 114.

Will the in step 106 On the other hand, if the query for the necessity of regeneration is answered in the affirmative, it is done in one step 108 a check of the temperature of the particulate filter 26 , If the temperature for regeneration is sufficiently high, in step 110 Regeneration is triggered or regeneration already started is continued. The regeneration takes place with the support of the secondary air supply. Subsequently, the procedure with the main program in step 100 continued.

Results in the step 108 by checking the temperature of the particulate filter against the fact that the temperature for triggering or continuing the regeneration is not sufficiently high, the program branches into the step 112 in which a heating of the preferably coated particle filter 26 is triggered. After triggering the heater, the procedure with the main program in step 100 continued. The heating is repeated in the process, for example, by negating the in step 106 query or by negating the temperature query in step 108 canceled. The heating steps 112 and 116 may differ from each other in terms of their implementation, for example, with regard to the respective amount of secondary air supplied.

Once regeneration has begun, it may be denied by the step 106 completed query.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 102012221549 A1 [0051]
• DE 102006011894 A1 [0051, 0052]

Claims (12)

A method for heating and regenerating a in the exhaust stream of a gasoline engine (10) downstream of a catalyst (30) arranged particulate filter (26), wherein the gasoline engine (10) comprises a device (50) for supplying secondary air to the exhaust gas flow between the catalyst (30) and the Particulate filter (26), characterized in that - the gasoline engine (10) and the device (50) for the supply of secondary air are controlled so that between the catalyst (30) and the particulate filter (26) predetermined values of an air ratio lambda result ; Output signals of a lambda probe (34) arranged in the exhaust gas flow between the catalytic converter (30) and the particle filter (26) and sensitive to oxygen as the exhaust gas constituent are detected, - a concentration of at least one further exhaust gas constituent is determined, and - the values of the air ratio Lambda depending on the detected output signals and additionally determined in dependence on the concentration of the at least one further exhaust gas component and taken into account in controlling the gasoline engine (10) and / or the device (50). Method according to Claim 1 , characterized in that the gasoline engine (10) and the device (50) for supplying secondary air - to heat the particulate filter (26) are operated so that a temporal average at the output of the catalyst (30) a first value of air ratio lambda adjusts a first excess fuel in the prevailing exhaust gas atmosphere and at the entrance of the particulate filter (26) averaged over time, a second value of the air ratio lambda, which corresponds to a stoichiometric composition of the prevailing exhaust gas atmosphere, and - that the gasoline engine (10) and the device (50) for supplying secondary air for the regeneration of the particulate filter (26) are operated so that a third value of an air ratio lambda, which sets a stoichiometric value or a second excess fuel in at the output of the catalyst (30) represents the prevailing exhaust gas atmosphere there, at least small r is the first excess fuel, and at the entrance of the particulate filter (26) adjusts a fourth value of the air ratio lambda, which corresponds to an excess of air in the prevailing exhaust gas atmosphere there. Method according to one of the preceding claims, characterized in that the concentration of the at least one further exhaust gas component from in a control unit (16) of the gasoline engine (10) available measured variables is modeled. Method according to one of the preceding claims, characterized in that the first value and the third value in a first exhaust system (14.1), in which a supply of secondary air to the exhaust gas flow between the lambda probe (34) and the particulate filter (26), by changes a combustion chamber lambda of the gasoline engine (10) is set. Method according to Claim 4 , characterized in that the second value and the fourth value are adjusted by changes in the supply of secondary air to the exhaust gas flow. Method according to one of the preceding claims, characterized in that as concentrations of further exhaust gas constituents concentrations of hydrogen and carbon monoxide are determined and that a time varying ratio of the concentration of hydrogen to the concentration of carbon monoxide at rich lambda at the outlet of the catalyst and different cross sensitivities of the lambda probe ( 34) for hydrogen and carbon monoxide are taken into account. Method according to Claim 2 or 3 , characterized in that the first value and the third value in a second exhaust system (14.2), in which a supply of secondary air to the exhaust gas flow between the catalyst (30) and the lambda probe (34), by coordinated adjustment of the combustion chamber lambda and the secondary air supply can be adjusted. Method according to Claim 7 , characterized in that the second value and the fourth value are adjusted by changes in the supply of secondary air to the exhaust gas flow. Method according to Claim 7 or 8th , Characterized in that are determined as the concentrations of other gas components concentrations of hydrogen and carbon monoxide and that a time-varying ratio of the concentration of hydrogen to the concentration of carbon monoxide in a rich lambda at the output of the catalyst (30) and the different cross-sensitivities of the lambda probe (34) be taken into account for hydrogen and carbon monoxide, and in addition, a cross-sensitivity of the lambda probe for oxygen and a taking place in the lambda probe Vorkatalyse of hydrogen with oxygen is taken into account. Gasoline engine (10) with a in the exhaust gas flow of the gasoline engine (10) arranged catalyst (30), a downstream of the catalyst (30) arranged particulate filter (26), a device (50) for supplying secondary air to the exhaust gas flow between the catalytic converter (30) and the particulate filter (26) and an oxygen-sensitive lambda probe (34) arranged between the catalytic converter (30) and the particulate filter (26), characterized in that the control device (16) is adapted to carry out the steps the procedure of Claim 1 or a method of Claims 2 to 9 perform. Computer program product having instructions for tracking the device Claim 10 to induce the steps of the procedure of Claim 1 or one of the Claims 2 to 8th perform. Computer-readable medium on which the computer program product of the Claim 11 stored in machine readable form.

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