DE102017003240A1 - A method for regenerating an exhaust aftertreatment device of a motor vehicle, computer program for performing the method and associated motor vehicle - Google Patents

Abstract

What is described is a method for regenerating an exhaust aftertreatment device of a motor vehicle, in which the motor vehicle has an internal combustion engine with which a crankshaft can be driven during operation. In operation, the exhaust gases are supplied to the exhaust aftertreatment device. In the method, the internal combustion engine is placed in a freewheeling operation, by decoupling the internal combustion engine from the drive train. Then, the crankshaft is driven with an auxiliary drive to produce an excess of oxygen in the exhaust aftertreatment device required for the regeneration of the exhaust aftertreatment device.

Description

The invention generally relates to a method for regenerating an exhaust aftertreatment device of a motor vehicle. In particular, the invention relates to a method for regenerating an exhaust aftertreatment device, in particular an exhaust gas particulate filter of a motor vehicle with an internal combustion engine, a computer program for carrying out the method.

Exhaust aftertreatment devices are used, inter alia, to purify exhaust gases, in particular exhaust gases from internal combustion engines, from environmentally harmful exhaust gas components such as, for example, NOx or exhaust gas particles. In the course of operation exhaust-gas particulate filters settle due to soot particles present in the exhaust gases. To maintain functionality, the exhaust aftertreatment devices undergo a regeneration process.

Object of embodiments of the invention is to provide a method for regenerating an exhaust aftertreatment device of an internal combustion engine and especially an exhaust particulate filter of a motor vehicle.

According to a first aspect, a method for regenerating an exhaust gas aftertreatment device of a motor vehicle, in particular a particle filter for gasoline engines or a GPF (gasoline particle filter) or a particulate filter for diesel engines or a DPF is specified. The motor vehicle has an internal combustion engine, in particular a gasoline or diesel engine. In the internal combustion engine, during operation, i. when it is on and cylinders are fired, a crankshaft drivable in a known manner and the exhaust gases are fed to the exhaust aftertreatment device.

The proposed method comprises in a first step, the displacement of the internal combustion engine in a freewheeling operation, which takes place by decoupling the internal combustion engine from the drive train. When freewheeling, also called sailing or coasting in English, the vehicle rolls thanks to its kinetic energy without drive, the internal combustion engine can either be on or off. In freewheeling operation, the internal combustion engine is not dragged, so that the rolling phase over the coasting longer fails, which helps save fuel.

Upstream of this step, an event triggering the coasting operation can be detected by suitable sensors, in particular an actuation of the vehicle clutch by the driver, in the presence of a manual or automatic transmission, a shift to normal gear, or a release of the accelerator pedal by the driver, what complete or almost completely. In an automatic transmission or in the presence of a supplement to an electronic clutch manual transmission, the internal combustion engine is automatically decoupled from the drive train or the running of the engine to the drive wheels power flow is interrupted.

The method further comprises a step of driving the crankshaft with an auxiliary drive to produce an excess of oxygen required for the regeneration of the exhaust aftertreatment device.

Due to the excess of oxygen in the exhaust aftertreatment device, a so-called passive regeneration process may be initiated by burning the soot particles or deposits present in the exhaust aftertreatment device in an oxygen-rich atmosphere within the exhaust aftertreatment device, whereby the exhaust aftertreatment device may regenerate.

In contrast to the known overrun cutoff (called DFCO or Deceleration Fuel Cut-Off operation), in which the fuel supply is interrupted when the accelerator pedal is released and in which the internal combustion engine is not decoupled from the drive train, according to the proposed method Vehicle dynamics during the freewheel through the drive train is not affected, ie it does not come to a braking effect as by the tow of the internal combustion engine. Furthermore, unlike the passive regeneration process in the fuel cut, the regeneration process of the exhaust gas aftertreatment device is not affected or impaired by the running state of the vehicle.

The method enables a controlled regeneration of the exhaust aftertreatment device during a freewheeling operation of the motor vehicle. In the fuel cut, however, a free adjustment of the speed and thus a controlled regeneration is not readily possible because the speed of the engine is coupled in overrun at the currently engaged gear and the vehicle speed.

In addition, the method can also be used in vehicles which have a start-stop functionality or in which the internal combustion engine is automatically switched off in freewheeling phases, because according to the method, a running operation of the internal combustion engine is not required. Rather, the (forced) rotation of the crankshaft ensures that the for the Regeneration process required oxygen is promoted to the exhaust aftertreatment device. For this purpose, it must only be ensured that intake and exhaust valves are open at the same time, so that oxygen-containing fresh air coming from the intake tract, thanks to an existing pressure gradient, can flow through the combustion chambers of the internal combustion engine and flow into the exhaust gas tract with its exhaust aftertreatment device. In this operating phase, the internal combustion engine acts, so to speak, like an air pump, which conveys the fresh air to the exhaust aftertreatment device.

In one embodiment of the method, after the step of displacing the internal combustion engine into a freewheeling operation, the internal combustion engine is switched off, whereby the fuel consumption is reduced.

In a further embodiment of the method, the auxiliary drive drives the crankshaft at about 100 to about 300 revolutions per minute. This compared to the normal idle speed reduced speed can be achieved with an electric motor. The electric motor may be arranged in the power flow direction after the internal combustion engine, so that the internal combustion engine and the electric motor are arranged in series.

The method can be configured such that the speed to be reached by the auxiliary drive is kept essentially constant at least in sections of time. Substantially constant in this context means that the rotational speed is kept constant within the scope of the measuring or setting accuracy, in particular from approximately 5% to 10%. In this way, the oxygen excess in the exhaust gas aftertreatment device can be kept substantially constant, so that reproducible results can be set at the set value of the excess oxygen and the regeneration can take place in a controlled manner.

The driving of the crankshaft can be done by a combined electric motor-generator unit with belt or chain drive (English: belt alternator starter - BAS) or by the electric motor. It is also possible to use a manual transmission equipped with an electric motor (English electrified manual transmission - eMT). In this, the electric motor is used to hybridize the manual transmission by imposing a torque in defined operating phases of one of the transmission shafts, so that when the clutch is engaged, the crankshaft can also be driven. Also possible is a (separate) electric motor arranged in the power flow direction downstream of the internal combustion engine instead of the electric motor of BAS or eMT.

The switching off of the internal combustion engine can take place in particular without additional load by a gradual or gentle, in particular not abrupt, reduction of the fuel supply up to the interruption of the fuel supply. By gradual or gentle reduction of the fuel supply without additional load, the shutdown of the engine can be performed in a particularly gentle on the engine.

The method may include performing a diagnostic or a diagnostic test during the freewheeling operation, in particular when the freewheeling operation takes place with the internal combustion engine switched off. In contrast to overrun operation, a free design or implementation of diagnostic tests is possible in free-running operation due to the decoupling of the internal combustion engine from the drive train, without influencing or adversely affecting the driving behavior of the vehicle.

In addition, by performing the diagnostics during the freewheeling operation, the quality or the success rate of the diagnostics can be increased while at the same time minimizing the CO ₂ emission.

In freewheeling operation, an operating state of the internal combustion engine can be set via at least one operating parameter. The operating parameter is in particular a rotational speed and / or a load of the internal combustion engine. By doing so, the diagnostics can be performed at different operating modes of the internal combustion engine.

The at least one operating parameter of the internal combustion engine may also include a time-variable operating parameter of the internal combustion engine. The temporal variability of the at least one operating parameter of the internal combustion engine enables diagnostics under different dynamic conditions of the internal combustion engine.

When performing the diagnostics, the internal combustion engine with a variable load, in particular by the auxiliary drive, are acted upon. By subjecting the internal combustion engine with a variable load driving situations with variable load of the internal combustion engine can be simulated during the diagnostic test.

Setting the operating state of the internal combustion engine comprises adjusting an operating state similar to an engine idling. As a result, diagnostic tests can be carried out to investigate the idling behavior of the internal combustion engine.

The internal combustion engine can during the diagnostic test of the auxiliary drive are driven, that the driving of the internal combustion engine corresponds to a driving of the internal combustion engine by the drive train during a coasting operation of the vehicle. As a result, an overrun fuel cutoff can be simulated during the diagnostic test, in particular for the diagnosis of an O ₂ sensor or catalytic converter, without, however, influencing the driving behavior of the vehicle.

During the diagnostic test, the speed or the load of the internal combustion engine can be selected at the lowest possible level, in particular without impairing the validity of the diagnostic test. As a result, the oxygen enrichment of the exhaust gas or the excess of oxygen for the regeneration of the exhaust aftertreatment device can be maintained.

During the diagnostic test, the torque developed by the internal combustion engine can be detected and evaluated. In the evaluation, in particular the fact can be taken into account that the torque detected in the diagnostic test can tend to be lower. For if the speed of the internal combustion engine is adjusted by the auxiliary drive, any friction forces will be overcome by the auxiliary drive and not by the internal combustion engine.

The internal combustion engine may have a particularly adjustable throttle valve, and the excess oxygen in the exhaust gas aftertreatment device may through a wide opening, in particular by a more than 70% or 80% opening and each up to 100%, in particular by a maximum or full opening , the throttle valve are generated in the shutdown internal combustion engine.

Owing to the open throttle valve when the internal combustion engine is switched off, the oxygen can flow through the internal combustion engine without chemically reacting with a fuel within the internal combustion engine. The wide or full opening of the throttle valve also ensures that sufficient oxygen is available for efficient regeneration.

At least one current exhaust gas parameter can be detected by means of an exhaust gas aftertreatment device connected downstream of the exhaust gas engine. The regeneration process is terminated when the detected at least one actual exhaust gas parameter, for example an oxygen value, in particular an oxygen concentration or a parameters correlating with these parameters to determine that the exhaust aftertreatment device has substantially or substantially regenerated.

By the exhaust gas aftertreatment device downstream exhaust gas sensor thus the regeneration process can be controlled to the effect that the regeneration process or the (forced) rotation of the internal combustion engine is only performed when this is really necessary. As a result, the regeneration process can be carried out efficiently overall.

As the at least one current exhaust gas parameter, a current oxygen concentration in the exhaust gas can be used, wherein the regeneration process is ended when the oxygen concentration exceeds a predefined value. The oxygen concentration or the temporal change in the oxygen concentration in the exhaust gas downstream of the exhaust aftertreatment device can serve as an indication of the extent to which the process of combustion of deposits or soot particles in the exhaust gas aftertreatment device has progressed. For example, if all deposits in the exhaust aftertreatment device completely burned, the oxygen concentration after the exhaust aftertreatment device is maximum.

As the at least one current exhaust gas parameter, a current CO ₂ concentration or a current particle concentration in the exhaust gas can be used, wherein the regeneration process is terminated when the CO ₂ concentration or the fine particle concentration falls below a predefined value.

The CO ₂ concentration or particulate concentration in the exhaust gas downstream of the exhaust aftertreatment device may also serve as an indication of the extent to which the process of combustion of particulate matter in the exhaust aftertreatment device has progressed. For example, if all deposits in the exhaust aftertreatment device completely burned, the CO ₂ concentration is minimal.

As an additional drive of the internal combustion engine, an electric motor can be used.

By an electronic control of the electric motor, the speed of the forced rotation of the internal combustion engine or the load of the internal combustion engine can be set or kept constant during the diagnostic test in a simple manner.

The motor vehicle may be designed as a hybrid vehicle, which comprises an electric motor in addition to the internal combustion engine, and wherein the electric motor is used as an additional drive.

The motor vehicle can be embodied, in particular, as a hybrid vehicle with a BAS or Belt Alternator starter. In the BAS configuration, the electric motor and the engine may generate torque on a common axis.

The parallel arrangement of the electric motor and the internal combustion engine in the BAS configuration, the rotational speed of the internal combustion engine can be adjusted by the electric motor in a simple manner. In addition, the BAS configuration is characterized by a compactness, which allows a compact and lightweight design.

For the additional drive of the internal combustion engine, alternatively or cumulatively, a dedicated electric motor may be provided. The exhaust aftertreatment device may in particular comprise an exhaust gas filter and / or a catalyst.

The procedural regeneration process can easily increase the efficiency and the service life of the exhaust gas filter or of the catalytic converter.

The speed may be adjustable in a range of about 100 to 300 revolutions per minute. As a result, a sufficient excess of oxygen to carry out the regeneration can be generated. The speed can also be selected depending on a current temperature of the exhaust aftertreatment device, whereby an optimal for the current temperature speed can be adjusted.

The setting of the speed can be stored as a table or map in the internal combustion engine. In particular, the table may include a detected during the test measurements dependence between the current temperature of the exhaust aftertreatment device and the optimal speed of the internal combustion engine.

Using the table, the speed can be easily adapted to the current temperature of the exhaust aftertreatment device to optimize the regeneration process. The table is stored in a non-volatile memory, for example a flash memory, and the microprocessor of the engine control unit accesses it during the driving operation.

In other aspects, a computer program and a computer program product, i. proposed a computer-readable medium on which the computer program is stored, which is used to control a regeneration process of an exhaust aftertreatment device of a motor vehicle and which, when executed on a computing unit of a vehicle, instructs the arithmetic unit to perform the method described above. The computer program enables a controlled regeneration of the exhaust aftertreatment device during a freewheeling operation of the motor vehicle, in particular by maintaining a substantially constant speed of the forced rotation of the internal combustion engine.

There is also provided a motor vehicle comprising an internal combustion engine with an exhaust aftertreatment device and an electric motor. The motor vehicle is characterized by an efficient exhaust aftertreatment or filtering and by an environmentally friendly operation.

The motor vehicle may in particular be designed as a hybrid vehicle, which has an electric motor in addition to the internal combustion engine and is designed such that the internal combustion engine can be driven in the off state by the electric motor of the hybrid motor. As indicated above, the electric motor may be provided by a BAS or eMT or may be a separate electric motor.

• 1a zeigt schematisch ein Antriebssystem eines Kraftfahrzeugs gemäß einem Ausführungsbeispiel,
• 1b zeigt schematisch ein Antriebssystem eines Kraftfahrzeugs gemäß einem zweiten Ausführungsbeispiel,
• 1b zeigt schematisch ein Antriebssystem eines Kraftfahrzeugs gemäß einem dritten Ausführungsbeispiel,
• 2 zeigt ein Flussdiagramm eines Verfahrens zum Regenerieren einer Abgasnachbehandlungsvorrichtung nach einem Ausführungsbeispiel,
• 3 zeigt beispielhaft einen zeitlichen Ablauf des Freilaufbetriebs mit bzw. ohne Regeneration der Abgasnachbehandlungsvorrichtung.

The invention will now be explained in more detail with reference to the accompanying figures.

• 1a shows schematically a drive system of a motor vehicle according to an embodiment,
• 1b schematically shows a drive system of a motor vehicle according to a second embodiment,
• 1b shows schematically a drive system of a motor vehicle according to a third embodiment,
• 2 shows a flowchart of a method for regenerating an exhaust aftertreatment device according to an embodiment,
• 3 shows an example of a timing of the freewheeling operation with or without regeneration of the exhaust aftertreatment device.

1a schematically shows a drive system of a motor vehicle according to a first embodiment. The drive system 1 is a hybrid drive with an internal combustion engine 3 as well as an electric motor 4 ,

In this embodiment, the hybrid vehicle has a combined electric motor-alternator unit 4a , also called BAS (English: Belt Alternator Starter), the same time electric motor 4 and alternator 4b is what is through the dashed line 4c is indicated. It can both the internal combustion engine 3 as well as the electric motor 4 generate a torque to drive the crankshaft. The electric motor 4 and the internal combustion engine 3 are mechanically coupled via a belt drive, so that both the electric motor 4 as well as the internal combustion engine 3 over the same powertrain 5 can drive the motor vehicle. In regular driving the internal combustion engine drives 3 the motor vehicle and loads the as an alternator 4b the combined electric motor-alternator unit 4a the battery of the hybrid vehicle. When starting the vehicle, the electric motor is capable 4 to generate a torque around the crankshaft 6 to drive and about the internal combustion engine 3 to start, so that then the electric motor 4 acts as a starter.

The belt drive between the internal combustion engine 3 and the electric motor 4 is in 1 through a broad arrow 14 shown schematically. The power flow runs from the crankshaft 6 to the electronic clutch 8th , which is opened or closed as usual via particular electric actuators, so that the clutch pedal does not interfere with the clutch 8th is mechanically coupled. From the clutch 8th the power flow continues to the transmission 7 and from there in the double arrow direction to the drive wheels of the motor vehicle.

The drive system also includes an exhaust tract 9 with an exhaust aftertreatment device 10 , an exhaust gas sensor 11 , in particular an oxygen sensor, and an exhaust pipe 12 showing the internal combustion engine with the exhaust aftertreatment device 10 and with the exhaust gas sensor 11 combines.

The exhaust gas generated in the internal combustion engine is via the exhaust pipe 12 through the exhaust aftertreatment device 10 directed to an exhaust (not shown). The exhaust flow direction in the exhaust pipe 12 is by an arrow 13 shown. Through the exhaust gas sensor 11 located downstream of the exhaust aftertreatment device 10 is arranged, one or more parameters of the exhaust gas, in particular an oxygen content of the exhaust gas or another parameter correlating with the oxygen content, after the exhaust aftertreatment in the exhaust aftertreatment device 10 detected.

The exhaust gas sensor 11 allows diagnostics during, among other things, a freewheeling operation of the engine 2 , In particular, on the basis of the exhaust gas sensor 11 recorded data, the regeneration process of the exhaust aftertreatment device 10 to be controlled. By controlling the regeneration process, in particular the optimal operation of the exhaust aftertreatment device can be ensured.

In the embodiment shown, the exhaust aftertreatment device comprises 10 a catalyst 14 as well as a particle filter or GPF 15 for gasoline engines (Gasoline Particle Filter). In an embodiment with a diesel internal combustion engine, the exhaust aftertreatment device may be formed as a diesel particulate filter.

The exhaust gas sensor 10 detects a current oxygen content in the exhaust gas, the value of which, inter alia, on the efficiency of the exhaust aftertreatment device 10 can close back.

1b indicates one 1a alternative embodiment, in which like reference numerals designate like objects. In this design, no BAS is used, but a separate electric motor 4d that is between internal combustion engine 3 and clutch 8th is arranged. The functionality is as described above. In the further embodiment of 1c is the electric motor 4e mechanically to the gearbox 7 coupled and on the one hand with the clutch open 8th and closed clutch 8 'apply torque to a transmission shaft and drive the vehicle, but on the other hand, with the clutch engaged 8th and preferably open clutch 8 ', the crankshaft 6 drive.

2 FIG. 12 shows a flowchart of a method for regenerating an exhaust aftertreatment device according to an embodiment.

The flowchart 100 shows in particular process steps in the regeneration of the exhaust aftertreatment device 10 , starting from a starting situation 101 or from an initial state 101 when a vehicle with the propulsion system 1 of the 1 and powered by the internal combustion engine 3 is driven.

From a starting situation 101 without freewheeling, in the polling step 110 queried whether a freewheeling operation or coasting operation or coasting of the vehicle triggering event, for example, the actuation of the clutch by the vehicle driver, has taken place.

Will in the query step 110 determined that no freewheel triggering event has taken place, the journey is continued without freewheeling operation. If, however, the freewheel triggering event has taken place, the freewheeling operation of the vehicle is activated or the vehicle is put in the freewheeling mode, which is the box 120 in the flowchart.

The freewheel can be triggered in particular when the driver takes his foot off the gas pedal. Then the drive train is automatically decoupled from the engine by the automatic transmission or by means of an electronic clutch, for example in vehicles with manual transmission.

During the freewheeling operation, in the polling step 130 queried whether a regeneration of the exhaust aftertreatment device 10 is required. This can in particular be based on that of the exhaust gas sensor 11 recorded data.

Will in the query step 130 found that a regeneration of the exhaust aftertreatment device 10 is required is in the process step 140 the internal combustion engine 3 slowly shut off, especially without abruptly stalling the fuel supply. This is the internal combustion engine 3 shut down without an additional load at wide or fully opened throttle. The shutdown of the internal combustion engine 3 can be done in particular by interrupting the fuel supply.

This is followed by a step 160 the regeneration of the exhaust aftertreatment device 10 at a low speed of the internal combustion engine 3 , This is the internal combustion engine 3 forced to rotate at a constant speed by an auxiliary drive. As an additional drive of the internal combustion engine 3 can the electric motor 4 be used.

Depending on the embodiment, a dedicated electric motor or the starter motor of the internal combustion engine can also be used to drive the crankshaft 3 be used. The rotation of the crankshaft by the auxiliary drive generates the excess oxygen required for the regeneration, the adjustability of the rotational speed allowing a controlled regeneration process.

In the query step 170 is queried whether the regeneration of the exhaust aftertreatment device 10 is completed or whether the exhaust aftertreatment device 10 no further regeneration needed. This can in particular be based on that of the exhaust gas sensor 11 recorded data.

Will in the query step 170 found that the regeneration of the exhaust aftertreatment device 10 not yet completed, so the regeneration process in the process step 160 continued. On the other hand, in the query step 170 If the regeneration process has been determined to have been completed, the vehicle returns to the normal free-running mode or to the step 120 back.

According to another embodiment, the method includes performing a diagnostic test.

The diagnostic test can in particular during the freewheeling operation, ie after the process step 120 , be performed. During the diagnostic test, one or more operating parameters of the internal combustion engine may be set according to a test to be performed. In particular, the internal combustion engine can be acted upon during the diagnostic test with a variable load, in particular by the auxiliary drive.

In particular, the diagnostic test after the query step 130 be performed if in the query step 130 it is stated that a regeneration of the exhaust aftertreatment device 10 is not required.

According to an embodiment, the diagnostic test may be after the query step 170 be performed if in the query step 170 it is stated that the regeneration of the exhaust aftertreatment device 10 is completed.

According to an embodiment, the diagnostic test may be combined with a regeneration process of the exhaust after-treatment device. In particular, during the diagnostic test, the speed or the load of the internal combustion engine can be kept so low that an oxygen excess or oxygen enrichment required for the passive regeneration of the exhaust gas aftertreatment device is achieved in the exhaust gas aftertreatment device.

3 shows an example of a timing of the freewheeling operation with or without regeneration of the exhaust aftertreatment device.

The upper curve shows an exemplary dependency of the vehicle speed v = v (t) of the time t schematically. At a certain time t ₀ , the freewheel triggering event takes place, followed by a freewheeling or coasting phase in which the vehicle speed decreases monotonically. At the end of the freewheeling phase, the vehicle driven again by the internal combustion engine accelerates, which can be seen from the increase in the value of v (t) after time t ₂ .

The timing of the freewheeling operation is based on the speed RPM (revolutions per minute) of the internal combustion engine 3 and the oxygen supply P (O ₂ ) in arbitrary units to the exhaust aftertreatment device 10 clarified.

These parameters are respectively for the freewheeling operation without or with the regeneration of Exhaust after-treatment device shown. The lower curve corresponds to the freewheel in the regeneration mode. The regeneration mode is indicated by index R.

As can be seen from the time dependency of the engine speed RPM without regeneration of the exhaust aftertreatment device, the RPM speed decreases sharply immediately after the initiation of the coasting operation at the time t ₀ , and the entire remaining time of the coasting operation remains at the zero level a complete shutdown of the internal combustion engine corresponds.

This is the case, for example, when the internal combustion engine is automatically switched off by a start-stop control upon detection of an event triggering the freewheel-for example, an actuation of the clutch. At the end of the coasting phase or freewheeling phase at time t ₂ , the internal combustion engine is restarted in particular by the start-stop control and the rotational speed RPM rises again.

In the regeneration mode, the RPM _R decreases after the time t ₀ altogether slower down to a speed of about 200 revolutions per minute, which then until the completion of the regeneration process at time t ₁ based on the rotation by the electric motor 4 is kept constant.

The lower two curves show the oxygen supply P (O ₂ ) without (the upper of the two curves) and with the regeneration.

As can be seen in the upper curve, the oxygen supply without regeneration operation with the shutdown of the internal combustion engine 3 relatively quickly, in particular interrupted together with the collapse in the rotational speed (RPM), so that no oxygen is supplied in the entire freewheeling phase of the exhaust gas aftertreatment device.

When freewheeling with the regeneration of the exhaust aftertreatment device, however, the oxygen supply increases rapidly and remains until the time t ₁ or until the completion of the regeneration process at a relatively high level. This increase in the oxygen supply P _R (O ₂ ) is due to the wide or full opening of the throttle valve of the internal combustion engine. The opening angle of the throttle valve can be selected in the range of about 70 ° to about 90 °, in particular from about 80 ° to about 90 °, where 0 ° is a fully closed and 90 ° (this corresponds to an opening of 100% ) means a fully open throttle.

Increasing the oxygen supply results in sufficient oxygen excess to initiate passive regeneration of the exhaust aftertreatment device, such that the overrun phase of the vehicle is efficient for regeneration of the exhaust aftertreatment device 10 can be used.

Is particularly based on the of the exhaust gas sensor 11 detected data has found that the exhaust aftertreatment device has largely recovered or regenerated, so there is no need to continue the regeneration of the exhaust aftertreatment device 10 , The oxygen supply or the rotation of the internal combustion engine 3 through the electric motor 4 can thus be stopped.

The termination of the regeneration process takes place in this example at the time t ₁ , which can be seen from the fact that the speed RPM _R drops back to zero, and until the end of the freewheeling phase, ie until the time t ₂ remains at the zero level ,

Although at least one exemplary embodiment has been shown in the foregoing description, various changes and modifications may be made. The above embodiments are merely examples and are not intended to limit the scope, applicability, or configuration of the present disclosure in any way. Rather, the foregoing description provides those skilled in the art with a scheme for practicing at least one example embodiment, which may make numerous changes in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the appended claims and their legal equivalents ,

LIST OF REFERENCE NUMBERS

1

drive system

2

engine

3

Internal combustion engine

4

electric motor

4a

combined electric motor-alternator unit

4b

alternator

4c

stroke

4d

electric motor

4e

electric motor

5

powertrain

6

crankshaft

7

transmission

8th

clutch

9

exhaust tract

10

exhaust aftertreatment device

11

exhaust gas sensor

12

exhaust pipe

13

arrow

14

catalyst

15

particulate Filter

100

Flowchart of the process

101

Äusgangssituation

110

inquiry step

120

Freewheeling operation

130

inquiry step

140

Shutdown of the internal combustion engine

160

Regenerate

170

inquiry step

Claims (13)

A method of regenerating an exhaust aftertreatment device (10) of a motor vehicle, wherein the motor vehicle comprises an internal combustion engine (3) with which a crankshaft (6) is drivable during operation and whose exhaust gases are fed to the exhaust aftertreatment device, the method comprising the steps of: - Setting the internal combustion engine (3) in a freewheeling operation by decoupling the internal combustion engine (3) from the drive train (5); - Driving the crankshaft (6) with an auxiliary drive (14) for generating an excess of oxygen required for the regeneration of the exhaust aftertreatment device (10) in the exhaust aftertreatment device (10). Method according to Claim 1 wherein, after the step of displacing the internal combustion engine (3) into a freewheeling operation, the internal combustion engine (3) is switched off. Method according to Claim 1 or 2 wherein the auxiliary drive drives the crankshaft (6) at about 100 to about 300 revolutions per minute. Method according to one of Claims 1 to 3 in which a rotational speed of the crankshaft (3) that is substantially stable at least for a certain period of time is selected. Method according to one of the preceding claims, in which an electric motor (4) of a combined electric motor-generator unit (4a), an electric motor (4e) assigned to a manual transmission (7) or an electric motor (4d) arranged in the direction of power flow downstream of the internal combustion engine (3) the crankshaft (3) drives. Method according to one of the preceding claims, in which the decoupling of the internal combustion engine (3) from the drive train by an electronic clutch (8). Method according to one of the preceding claims, wherein the method comprises a diagnosis during the freewheeling operation, wherein the setting of the operating state comprises adjusting at least one operating parameter of the internal combustion engine (3). Method according to Claim 7 , wherein when performing the diagnostics, the internal combustion engine (3) is subjected to a variable load. Method according to one of the preceding claims, wherein the internal combustion engine (3) comprises a throttle valve, and wherein the excess oxygen in the exhaust gas aftertreatment device (10) by a wide opening of the throttle valve with the internal combustion engine (3) is turned off. The method according to claim 1, wherein at least one current exhaust gas parameter is detected by means of an exhaust gas after-treatment device downstream of the exhaust gas after-treatment device, and wherein the internal combustion engine is set back into the free-wheeling operation without driving the crankshaft when Based on the detected at least one current exhaust gas parameter is determined that the exhaust aftertreatment device (3) has regenerated. Method according to one of the preceding claims, wherein the adjustment of the rotational speed as a function of a current temperature of the exhaust gas aftertreatment device (10). A computer program for controlling a regeneration process of an exhaust aftertreatment device of a motor vehicle, which, when executed on a computing unit of a vehicle, instructs the arithmetic unit, a method according to one of Claims 1 to 11 perform. Motor vehicle according to claim 14, wherein the motor vehicle in addition to the internal combustion engine (3) has an electric motor (4,4d) and is designed such that the crankshaft (6) when switched off Internal combustion engine (3) by the electric motor (4,4d) can be driven.

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