DE102017212909A1 - Method for controlling and / or regulating the exhaust aftertreatment in a motor vehicle and control device - Google Patents

Abstract

Method for controlling and / or regulating exhaust gas aftertreatment in a motor vehicle, in which at least one exhaust-gas component (20) is arranged to control and / or regulate a special operation, in particular a regeneration, at least one discontinuously operating, in particular regenerable and / or converting, exhaust gas component Temperature from the exhaust system (20) is used. Optimized control and / or regulation is achieved by predicting the future temperature from the exhaust tract (20) model-based, including route data and / or additional data supplementing the vehicle data to improve operating point prediction.

Description

State of the art

The invention relates to a method for controlling and / or regulating the exhaust aftertreatment in a motor vehicle, wherein at least one arranged in an exhaust tract discontinuously operating, in particular regenerable and / or converting, exhaust gas component for controlling and / or regulating a special operation, at least a temperature is used from the exhaust tract. Furthermore, the invention relates to a control device for carrying out the method.

The use of regenerable exhaust gas components in exhaust aftertreatment, such as NO _x storage catalytic converters or particulate filters, requires adapted control concepts in order to optimally optimize their discontinuous regeneration. Thus, for example, a NO _x storage catalytic converter for storing nitrogen oxides (NO _x ) from the exhaust gas at today's standard dimensions while driving can reach its storage capacity limit within a few minutes and must be regenerated (DeNOx regeneration) in order to restore the storage capacity and possible slip of NO _x by desorption. The regeneration then takes place under certain boundary conditions, for example at a certain elevated exhaust gas temperature level between eg 400 ° C - 500 ° C and / or in rich operation in the storage component. Since NO _x storage catalysts inherently sulfur oxides (SO _x ) can store, which are also present in the exhaust gas (by sulfur in the fuel and / or engine oil), NO _x storage catalysts must also be regenerated with respect to stored sulfur (DeSOx regeneration). As a rule, a further increased exhaust gas temperature level of, for example, 650 ° C.-700 ° C. and a longer regeneration time until complete emptying are necessary. The desulfurization temperature is close to the thermal damage of the NO _x storage catalyst, so that exceeding the temperature during regeneration, the NOx storage efficiency can irreversibly decrease.

Due to these circumstances, the inclusion of temperatures from the exhaust gas tract can be advantageous in the control and / or regulation of the regeneration. For example, from the DE 10 2012 010 189 A1 A method for regenerating a particulate filter of a vehicle is known, wherein, for example, the temperature of the particulate filter is detected and on the basis of which a current driving operation can be classified as favorable for the regeneration, average and unfavorable. In this case, a prognosis of the future driving operation can be made, and the time of regeneration are shifted to predicted phases of a favorable driving operation.

The present invention has for its object to provide an optimized method for controlling and / or regulating the exhaust aftertreatment in a motor vehicle, in particular the regeneration of a regenerable component and a corresponding control device for performing the method.

Disclosure of the invention

The object is achieved for the method with the features of claim 1 and for the control device with the features of claim 12.

According to claim 1, it is provided that the future temperature is predicted model-based from the exhaust tract, wherein track data and / or additional data supplementing the vehicle data, eg for improving the operating point prediction, are included. Route data form data which characterize the route conditions of the route traveled on a current journey in the future, including traffic information data. These arise for example because of the route and / or the current traffic situation and can be obtained from various sources, for example from navigation data, GPS data or the like. Additional data can form data for driver identification, date, time, place of departure, tank level data or data from further vehicle sensors, etc., which can be obtained, for example, via in-vehicle and / or mobile data communication and used for prediction. Such data may supplement vehicle data such as vehicle speed, vehicle position, vehicle operating state and / or data on driver actions on the vehicle and in total allow a prediction of the temperature over possibly longer time horizons and / or with improved accuracy. In this case, based on route data and / or additional data and / or vehicle data, future operating points of the engine are predicted and from this at least one temperature of the exhaust gas at one or different locations and / or the temperature (s) of at least one exhaust gas component j is predicted in a temperature prediction unit. A possible method for predicting the temperature is for example from DE10 2016 213 147.8 the applicant known. In the temperature prediction, for example, caloric variables of the exhaust gas and / or components from the exhaust gas tract are included. As a result, the engine control system will also have information about the thermal state of these components with a specific one for engine operation in the future Probability ahead. It is also possible to determine route data and / or additional data with the temperature (s) from the empirical connection of the future temperature (s). The information may be used to optimize the control and / or regulation of exhaust aftertreatment components. As a result, it is advantageously possible to minimize pollutant emissions while minimizing fuel consumption. Even discontinuous diagnostic procedures can be optimized and the durability of components can be increased.

The accuracy of the method can be increased by further including an actual value of the temperature (s).

In a preferred variant of the method, the temperature used is an exhaust gas temperature and / or component temperature upstream and / or in and / or downstream of the discontinuously operating, in particular regenerable, exhaust gas component which forms a reference temperature. In this case, a plurality of temperatures can be used as reference temperatures, and / or from a plurality of temperatures, a reference temperature can be created, for example, from an averaging. Setting specific reference temperatures at specific locations can increase the accuracy of the procedure.

Preferably, future road sections and / or operating times are identified in which the reference temperature (or the plurality of reference temperatures) will be within or outside a regeneration window due to the operation of the motor vehicle without the fuel consumption increasing the temperature range required for a desired regeneration operation Temperature (s) includes. Since, in particular during the desulfurization operation, a considerable temperature increase occurs, the regeneration window can also include temperatures which, in normal operation, are below the temperatures relevant for regeneration. These are then brought into the range of the temperature range required for the regeneration by the temperature elevation. In this way, the method can be optimized especially with regard to fuel consumption.

Preferably, future route sections and / or operating times are identified, in which the reference temperature (or a plurality of reference temperatures) by the operation of the motor vehicle in the range Einspeicherfähigkeit and / or conversion ability of a downstream of the first regenerable and / or converting exhaust gas arranged further regeneratable and / or converting Exhaust gas component will lie. This allows in the presence of at least two regenerable exhaust gas components optimized for such a configuration control and / or regulation.

Particularly advantageous in terms of lower pollutant emissions with the lowest possible fuel consumption, the method can be applied when in an extended regeneration range, which lies between a first and above the first second threshold of the load, a consolidated release (including other and / or additional criteria compared to the release in the conventional regeneration area) of the regeneration is applied. In the presence of several regenerable exhaust gas components, the regeneration area may relate to the loading of one of the components.

In an advantageous variant of the method, the consolidated release for a DeSOx or DeNOx regeneration takes place after reaching a sufficiently long route section or a sufficiently long operating time in which the reference temperature within the regeneration window for the corresponding regeneration operation, ie for desulfurization or NOx Outlet storage is. In such an operating window, regeneration can advantageously take place without temperature-increasing measures, in particular without additional fuel injection, as a result of which fuel consumption can be optimized. In one example of DeSOx regeneration, the consolidated release is issued when in normal operation a predicted reference temperature upstream of the NOx trap catalyst is in a regeneration window for DeSOx regeneration (ie, close enough to the desulfurization temperature of, for example, 650-700 ° C, s above) and a second predicted reference temperature in or downstream of the NOx storage catalyst during DeSOx regeneration for the duration of the regeneration operation below a temperature range in which thermal damage to the NOx storage catalyst would occur, for example 700 ° C or more.

Another variant results for a consolidated release of a DeNOx regeneration in the presence of two series-connected NOx storage catalysts, z. B. a close to the engine and a lower floor arranged. In this case, the release of a DeNOx regeneration can take place as a function of the predicted temperatures of the first and the second catalyst. In addition, the NOx level of the two catalysts can be taken into account. So z. B. at still relatively low level in one of the two catalysts release only at temperatures that occur for both catalysts within the corresponding Regeneration window lie. At high levels in both NOx storage catalysts, a favorable temperature within a regeneration window could already be sufficient with respect to one of the catalysts for consolidated release.

In another example, a NOx combination plant with z. B. a near-engine NOx storage catalyst and a downstream SCR catalyst for a selective catalytic reduction of NOx can be provided. Here, the release of the DeNOx regeneration of the NOx storage catalyst can take place at temperatures predicted in a regeneration window, when at the same time the SCR catalyst is in a temperature range of good conversion.

If, in particular, within the regeneration range predicted deviations of the reference temperature from the regeneration window of more than a maximum deviation in the immediate future, especially during a started regeneration, the started regeneration is stopped consolidated, the regeneration can be prevented in an unfavorable operating window and the regeneration be restarted in a cheaper operating range. In this case, as in the aforementioned example for the DeSOx regeneration, two or more reference temperatures can be used for the assessment. Preferably, the respective temperature limits for release (regeneration window) and abort differ by an offset value. This hysteresis prevents unwanted multiple jumps between release and termination of the regeneration due to temperature fluctuations.

In a further preferred variant of the method, the regeneration requirement of the first regenerable exhaust gas component is suppressed in the presence of a second, downstream regenerable exhaust gas component, if the prediction of a suitable reference temperature (and optionally of the load) is expected to achieve the storage capacity of the second component. By achieving the storage capability of the second component, any possible slip of NOx of the first component can be absorbed by the second component.

For pollutant reduction in the exhaust gas, it is advantageous if measures for temperature control are requested for faster achievement and / or restoration and / or maintenance of the temperature-induced Einspeicherfähigkeit and / or conversion capability. Should z. B. fall the predicted temperature in the storage catalyst below a temperature range of the lower limit of Einspeicher- and / or conversion ability of about 180-200 ° C, measures can be taken to increase the exhaust gas temperature, wherein z. B. control interventions to influence injection, ignition and / or air system can be made. There are also heating measures with additional components such as electrical or chemical / physical heaters in the exhaust system possible. Should z. B. the predicted temperature in the storage catalyst exceed a temperature range of the upper limit of Einspeicher- and / or conversion capability of about 400-450 ° C, so measures can be taken to lower the exhaust gas temperature. These measures may also be of an internal engine type, e.g. by influencing the injection, ignition and / or air system. A significant influence is also due to additional control elements, such. As for air injection before the catalyst, or heat recuperating devices to achieve.

In a preferred embodiment of the method, above the second threshold value of the loading, a conventional release is used independently of the temperature prediction. As a result, an advantageous distinction of the control strategy can be made depending on the loading area. An overcharge of the storage catalytic converter due to a non-advantageous for the regeneration engine operation can be avoided, whereby the functionality of the discontinuously operating, in particular regenerable component can be ensured.

• 1 schematisch das Grundprinzip der Temperaturvorhersage des Verfahrens,
• 2 schematisch einen Teil eines Abgastrakts mit diskontinuierlich arbeitenden, insbesondere regenerierbaren Abgaskomponenten und unterschiedlichen Referenztemperaturen,
• 3 schematisch eine Regenerationssteuerung unter Einbeziehung einer modellbasiert vorhergesagten Temperatur und
• 4 ein Diagramm mit einem Beladungsverlauf über der Zeit und einem ersten und einem zweiten Schwellenwert.

The invention will be explained in more detail by means of embodiments with reference to the drawings. Show it:

• 1 schematically the basic principle of the temperature prediction of the process,
• 2 schematically a part of an exhaust gas tract with discontinuously operating, in particular regenerable exhaust gas components and different reference temperatures,
• 3 schematically a regeneration control involving a model-based predicted temperature and
• 4 a diagram with a loading curve over time and a first and a second threshold.

1 shows in a schematic flow diagram, the basic principle of the method according to the invention for controlling and / or regulating the exhaust gas aftertreatment, wherein the regeneration of a regenerable exhaust gas component, such as a NOx storage catalyst 26 . 28 (see. 2 ), including a model-based predicted temperature from an exhaust tract 20 (see. 2 ) is controlled and / or regulated. This will be a temperature prediction unit 10 that a control device 1 is assigned, route data 11 and / or additional data 12 fed. Within the temperature prediction unit 10 one or more reference temperatures are model-based predicted, in particular the exhaust gas temperature (s) 13 at one or more points in the exhaust tract 20 and / or component temperature (s) 14 at one or more locations j in the exhaust tract 20 represent. This is done in the temperature prediction unit 10 the prediction of future operating ranges of the vehicle engine, on the basis of which, preferably including caloric variables from the exhaust tract, the temperatures are predicted model-based. The prediction of the future operating ranges can also be done in another unit and / or controller and the temperature prediction unit 10 be transmitted. The embedding in the entire regeneration control 30 is determined by 3 explained.

2 schematically shows a part of the exhaust tract 20 with discontinuous, eg regenerable and / or converting exhaust gas components 26 . 27 . 28 , 29 , here eg NOx storage catalysts 26 . 28 and sensors 27 . 29 , with respect to which reference temperatures can be determined. Further additionally or alternatively possible reference temperatures are exhaust gas temperatures eg at the positions 21 and or 22 (within the component 26 ), at a third position 23 between the components 26 and 28 , within the component 28 at a fourth position 24 and / or downstream of the components 26 . 28 at a fifth position 25 ,

In 3 is a simplified regeneration control 30 shown using a model-based predicted temperature. Here is a conventional regeneration control 31 in combination with a modified regeneration control 32 (outlined by the dashed line) shown in the present regeneration control 30 interact. The conventional regeneration control 31 has a control module 31.4 on, as the current data from a NOx loading model 31.1 Information about the current NOx load, from a SOx loading model 31.2 Information about the current SOx load and further from a module 31.3 Information about a current engine operating point, such as an engine speed n and a torque M, are supplied. The module 31.3 For example, it may correspond to the engine controller, or at least one module thereof.

In the control module 31.4 Based on current data different requirements with respect to the regeneration operation are determined, for example, depending on current relevant data, in particular loads, engine operating point and / or reference temperature / s in the exhaust system 20 , Implementation possibilities of a regeneration evaluated and if necessary a DeNOx requirement 31.5 , a DeSOx request 31.6 , a DeNOx crash 31.7 or a DeSox crash 31.8 can be issued.

This information of conventional control 31 be in conjunction with the modified regeneration control 32 a temperature involving regeneration control 33 fed. In this case, the temperature including regeneration control 33 In addition, the current load to be supplied. In addition, the temperature including regeneration control 33 Exhaust gas temperature (s) 13 and / or component temperature (s) 14 as reference temperatures from the temperature prediction unit 10 fed. Depending on the load can now in an extended regeneration area 46 (see. 4 ) a consolidated release of the regeneration are applied, in particular depending on the predicted reference temperature (s) a consolidated DeNOx requirement 34 , a consolidated DeSOx requirement 35 , a consolidated DeNOx crash 36 or a consolidated DeSOx abort 37 can be issued. Furthermore, a requirement for temperature control measures 38 to achieve a faster achievement and / or restoration and / or maintenance of the temperature-based storage capability of the regenerable component 26 and or 28 to achieve. At a loading above a second threshold 44 (see. 4 ), a conventional release of the regeneration is preferably applied independently of the temperature prediction, that of the conventional regeneration control 31 transmitted information is output.

4 shows a diagram 40 with a load 41 (eg, the first or second NOx storage catalyst 26 or 28 ) over time 42 and a first and second thresholds 43 . 44 , During vehicle operation there is an increasing load history 45 over time 42 , In a consolidated-release regeneration controller, it is in an extended regeneration region 46 already carried out a regeneration when based on the predicted temperature suitable for the regeneration reference temperature or a plurality of reference temperatures in particular without the fuel consumption increasing special measures in a regeneration window is identified lying. Such a load history with modified regeneration control is through the curve 48 shown. Here begins the regeneration in the extended regeneration area 46 at the beginning of regeneration 48.1 , The regeneration can be carried out until complete emptying of the regenerable component.

On the other hand shows curve 49 a regeneration process in a conventional regeneration area 47 above the second threshold 44 , From a start of regeneration 49.1 The regeneration begins, but even before complete discharge already at a time 49.2 due to an external event, such as a stop at a traffic light, must be canceled. This leads to an overall poorer ratio of additional fuel consumption to the converted pollutant mass.

This is how the diagram shows 40 by way of example, a possible advantage of the control and / or regulation of a special operation, in particular a regeneration, of a discontinuously operating, in particular regenerable, component which is controlled by taking into account a model-based predicted temperature.

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 102012010189 A1 [0003]
• DE 102016213147 [0006]

Claims (12)

Method for controlling and / or regulating the exhaust gas aftertreatment in a motor vehicle, wherein at least one temperature from the exhaust gas tract is arranged to control and / or regulate a special operation, in particular a regeneration, of at least one discontinuously operating, in particular regeneratable, exhaust gas component in an exhaust tract (20) (20) is used, characterized in that the future temperature from the exhaust tract (20) is predicted model-based, wherein track data and / or further, the vehicle data supplemental, additional data are included. Method according to Claim 1 , characterized in that an actual value of the temperature is included. Method according to Claim 2 , characterized in that at least one exhaust gas and / or component temperature (27, 29) upstream and / or in and / or downstream of the discontinuously operating, in particular regenerable, exhaust gas component is used, which forms at least one reference temperature. Method according to Claim 3 , characterized in that future route sections and / or operating times are identified, in which the reference temperature by the operation of the motor vehicle without the fuel consumption-increasing special measures will be inside or outside a regeneration window, which includes the temperature range of the temperature required for a desired regeneration operation. Method according to Claim 3 or 4 , characterized in that future route sections and / or operating times are identified, in which the reference temperature by the operation of the motor vehicle in the range of Einspeicherfähigkeit and / or conversion capability of a downstream of the first regenerable and / or converting exhaust gas arranged further regenerable and / or converting exhaust gas component will lie. Method according to one of the preceding claims, characterized in that in an extended regeneration area (46), which lies between a first and above the first lying second threshold (43, 44) of the load, a consolidated release of the regeneration is applied. Method according to Claim 6 , characterized in that the consolidated release for a desulfurization or DeNOx regeneration takes place after reaching a sufficiently long route section or a sufficiently long operating time, in which the reference temperature lies within the regeneration window for desulfurization or for NOx removal. Method according to Claim 6 or 7 , characterized in that in particular within the regeneration region (46) in prediction of deviation of the reference temperature from the regeneration window of more than a maximum deviation in the immediate future, especially during a started regeneration, the started regeneration is stopped consolidated. Method according to one of Claims 5 to 8th characterized in that the regeneration request of the first regenerable exhaust gas component is suppressed in the presence of at least one further, downstream regenerable and / or converting exhaust gas component if, on the basis of the prediction of a suitable reference temperature, the ability to accumulate and / or convert the further component before reaching the maximum Storage capacity of the first component is expected. Method according to one of the preceding claims, characterized in that measures for temperature control are required for faster achievement and / or restoration and / or maintenance of temperature-induced Einspeicherfähigkeit and / or conversion capability. Method according to one of Claims 6 to 10 characterized in that above the second threshold value (44) of the load a conventional release is applied independent of the temperature prediction. Control device (1) having a temperature prediction unit (10), which is designed to carry out the method according to one of the preceding claims, characterized in that the temperature prediction unit (10) is designed to have at least one device for detecting and / or transmitting route data and / or other additional data in data transmission connection.

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