DE102013004761A1 - Method for operating an automatic transmission of a motor vehicle, transmission control and motor vehicle with such - Google Patents

Abstract

The invention relates to a method for operating an automatic transmission (28) of a motor vehicle (10), a transmission ratio of the automatic transmission (28) depending on an operating point (n, L) of the motor vehicle (10) being predetermined from a stored shift map (42) and a switching signal (HSS, RSS) for controlling the transmission ratio of the automatic transmission (38) is output as a function of the predetermined transmission ratio. It is provided that the transmission ratio of the automatic transmission (28) is further predetermined as a function of a conversion efficiency of an exhaust gas aftertreatment device (20) with respect to at least one exhaust gas component.

Description

The invention relates to a method for operating an automatic transmission of a motor vehicle. The invention further relates to a transmission control set up for carrying out the method and to a motor vehicle comprising such a transmission control.

Automatic transmission (hereinafter also called automatic transmission) of motor vehicles are usually operated by means of a transmission control according to predetermined switching programs. This concerns in particular the specification of a gear stage, d. H. a gear ratio (gear), with which the transmission translates the engine speed of the internal combustion engine to the drive shaft of the traction tract of the vehicle. For this purpose, the transmission control accesses a stored shift map, which represent stored shift characteristics as a function of the current vehicle speed and a current load request by the driver. For each change between two successive gear stages is in each case a stored upshift characteristic for the upshifting of the lower gear stage in the next higher gear stage and a downshift characteristic for the downshift from the higher to the lower gear stage before. In other words, the shift map includes a set of upshift characteristics and a set of downshift characteristics. If, for example, during an acceleration of the vehicle an upshift characteristic curve is reached at a specific upshift point, the transmission control system controls the transmission with a corresponding upshift signal in order to shift it into the corresponding higher gearbox stage. The same applies to the downshift in a vehicle deceleration. In continuous automatic transmissions (CVT for continuous variable transmission), which can theoretically infinitely represent any transmission ratio, a shift map is also used for transmission control. However, this has no discrete shift characteristics, but a continuous map that represents the translation as a function of vehicle speed and load. However, such a continuous shift map can be considered as one of an infinite or at least a very large number of switching characteristics. In fact, today, for reasons of comfort, CVT transmissions are actually partially controlled according to discrete shift characteristics, i. H. according to a (fictitious) number of courses.

When determining the shift characteristics, the aim is always to match these to the lowest possible fuel consumption and thus low CO ₂ emissions. Accordingly, the shift characteristics are tuned to the lowest possible engine speeds (and thus higher loads). However, if the operating point is shifted in the direction of lower speeds and higher loads, the NO _x raw emissions increase disproportionately. Lean internal combustion engines, in particular diesel engines, generally have exhaust aftertreatment devices in order to convert the nitrogen oxides (NO _x ) emitted by the engine into harmless nitrogen (N ₂ ). Such NO _x exhaust aftertreatment components include, in particular, NO _x storage catalysts or SCR catalysts. Since the efficiency of such (and other) catalysts can be reduced with respect to the conversion of nitrogen oxides over the life of the catalyst compared to the new condition, for example due to catalyst poisoning, sulfurization or aging, it is usual, the switching points or switching characteristics always with a certain safety margin against a CO _2- optimized switching point vote. In practice, for this reason, a NO _x catalyst having a markedly reduced conversion efficiency is adopted to safely post-process the NO _x raw emission of the engine.

In the prior art it is also known to influence the switching points of an automatic transmission as a function of the catalyst temperature. In this case, after a cold start, when the catalyst is not yet ready for operation, the shift characteristics are adapted in the direction of higher vehicle speeds. In this way, the transmission is accelerated upshifting during acceleration and downshifted when decelerating premature and thus the engine at higher engine speeds and lower loads than usual driven. The higher exhaust gas temperatures produced in this way provide for an accelerated heating of the catalyst. Such a method is for example in US 3,895,541 or EP 1 410 935 A1 described. Although this strategy reduces the NO _x emissions of the internal combustion engine, fuel consumption and the associated CO ₂ emissions increase at the same time.

The invention is based on the object to provide a method for operating an automatic transmission of a motor vehicle, with the fuel consumption and thus the CO ₂ emissions of the engine are reduced, without an increase in Endemission pollutants of the exhaust gas, for example, NO _X , in purchasing to take. It is also intended to provide a transmission control system set up to carry out the method as well as a vehicle with the same.

This object is achieved by a method, a transmission control and a motor vehicle having the features of the independent claims.

The method for operating an automatic transmission of a motor vehicle according to the present invention provides to predetermine a transmission ratio of the automatic transmission in dependence on an operating point of the motor vehicle from a stored shift map and output depending on the predetermined gear ratio, a switching signal for controlling the transmission ratio of the automatic transmission. According to the invention, the transmission ratio is additionally predetermined as a function of a conversion efficiency of an exhaust gas aftertreatment device with regard to at least one exhaust gas component.

By taking into account the performance of the exhaust aftertreatment device is possible to take a maximum raw emission of the exhaust gas component, as long as the performance of the exhaust aftertreatment device ensures its implementation, and interpret the gear ratio of the transmission in favor of low fuel consumption and low CO ₂ emissions. While in the prior art, the transmission control is not adapted to the actual conversion efficiency of the aftertreatment system and thus always a certain safety buffer to account for a possible catalyst damage must be maintained, the inventive method allows the spread of allowable pollutant raw emissions in favor of CO ₂ - and fuel consumption optimization. Since the catalytic conversion of the raw emissions of the respective exhaust gas component is ensured by the knowledge and consideration of the conversion efficiency, the method does not lead to increased pollutant emissions.

In the context of the present invention, the term "raw emission" is understood to mean an emission of an exhaust gas component emitted by the internal combustion engine, ie before the aftertreatment in the exhaust gas tract. By contrast, "endemission" refers to the emission of an exhaust gas component released into the environment at the outlet of the exhaust tract, ie after aftertreatment.

In a preferred embodiment of the method, the transmission ratio of the transmission is predetermined so that while maintaining a concentration threshold of the at least one exhaust gas component downstream of the exhaust aftertreatment device, a CO ₂ raw emission and / or fuel consumption of the internal combustion engine is as low as possible. In other words, the CO ₂ raw emission or the fuel consumption is reduced so far as the conversion performance of the exhaust gas aftertreatment device ensures the conversion of the associated raw emission increase of the exhaust gas component. In this way, the lowest possible CO ₂ emissions and fuel consumption are realized while maintaining high emissions safety.

Typically, the shift map indicates the gear ratio as a function of a vehicle speed or equivalent magnitude, as well as a vehicle load or equivalent magnitude. As equivalent variables for the vehicle speed are about the engine speed or the rotational speed of a drive shaft in question, which are directly proportional to the vehicle speed. For example, the vehicle load may be calculated from the current fuel injection amount or a pedal value of a pedal encoder, which is a measure of operator depression of an accelerator pedal and is typically detected electronically. If the automatic transmission is a classic non-continuous transmission with a certain number of fixed gear ratios (gears), the shift map preferably has a series of shift characteristics which respectively define shift points for a change between two consecutive gear ratios (gear shifts). Preferably, the shift map for each gear change contains in particular an upshift characteristic, which indicates the switching point for the change to the next higher gear at an acceleration of the vehicle, and each a Rückschaltkennlinie for the change to the next lower gear in the event of a deceleration of the vehicle.

In a preferred embodiment of the method, a minimum engine speed of the internal combustion engine is determined as a function of the conversion efficiency of the exhaust gas aftertreatment device, in which a raw emission of the relevant exhaust gas component is still sufficiently converted by the exhaust gas aftertreatment device. The gear ratio is then predetermined in dependence on the thus determined minimum engine speed (and depending on the operating point of the motor vehicle). The minimum engine speed can be easily determined from a NO _X map. In each case, a minimum engine speed is preferably determined for acceleration phases of the vehicle and a minimum engine speed for delays. In the case of a non-continuous automatic transmission in this case a minimum engine speed is determined after an upshift of the transmission ratio and a minimum engine speed before a downshift of the transmission ratio. This implementation is easy to implement and easy to implement.

In an advantageous embodiment of the method is for various predetermined conversion efficiencies of Exhaust after-treatment device each predetermined a switching map. For example, for five different efficiencies of the exhaust aftertreatment device, including high catalyst efficiency (eg, 95-100%, poor catalyst efficiency, and (eg, 50-60%) and three intermediate stages, one switching map may be provided In the case of a non-continuous transmission, this in turn means that a set of shift characteristics, in particular a set of upshift characteristics and downshift characteristics, is provided for each of the various conversion efficiencies ,

In an alternative embodiment of the invention, the control takes place only by means of a single switching characteristic map, which is designed, for example, for a high catalytic converter efficiency, which is adapted accordingly depending on the actual conversion efficiency of the exhaust gas after-treatment device. The adaptation can be effected in a simple manner, for example by the application of a correction factor determined in accordance with the determined conversion efficiency, or the like.

The conversion efficiency of the exhaust aftertreatment device is preferably read from an on-board diagnostic device. Today's vehicles are typically equipped with such diagnostic facilities that monitor the existing exhaust aftertreatment devices to effect appropriate interventions in the engine control or the issue of an error signal when not functioning properly. Such diagnostic devices for catalysts, for example, detect a concentration of the respective exhaust gas component downstream of the catalyst and set them in relation to a raw emission of the component, which in turn can be measured or determined from maps. Such diagnostic algorithms are well known and established. In this respect, the inventive method requires no additional equipment with sensors or the like, but uses existing data and components back. Alternatively, especially if no on-board diagnosis (OBD) is provided, of course, the conversion efficiency can also be determined directly in the context of the method, for which basically the same diagnostic methods as in OBD can be used.

In a particular embodiment of the method, the exhaust gas component is nitrogen oxides NO _x , the exhaust gas aftertreatment device being a catalyst for the conversion of nitrogen oxides. In particular NO _x storage catalysts and SCR catalysts come into question here. Both versions are customary for the aftertreatment of the exhaust gas of predominantly lean-burned internal combustion engines, in particular diesel engines.

Particularly in the case of NO _x as an exhaust gas component, the inventive method provides that at a high conversion efficiency of the exhaust aftertreatment device, a smaller gear ratio, ie in non-continuous transmissions a higher gear and thus lower speeds, is predetermined than at a comparatively lower conversion efficiency. The reason for this is to be seen in the fact that with lower rotational speeds the NO _x raw emission of the internal combustion engine increases and thus requires a more effective after-treatment by the catalyst system. In contrast, with a lower conversion efficiency, a higher gear ratio and thus a higher speed must be predetermined in order to reduce the NO _x raw emissions to a convertible level. In the case of discrete switching characteristics, this means that at a high conversion efficiency of the aftertreatment device at least one switching characteristic is at least partially shifted in the direction of a higher vehicle speed or the equivalent size and vice versa. Thus, in the case of vehicle acceleration, the transmission is prematurely upshifted with high conversion efficiency, while upshifting is delayed with lower conversion efficiency.

Another aspect of the present invention relates to a transmission controller for an automatic transmission that is configured to carry out the method according to the invention.

Furthermore, the present invention relates to a motor vehicle, comprising an internal combustion engine, an automatic transmission and a transmission control thereof, which is adapted to control the automatic transmission according to the inventive method.

Further preferred embodiments of the invention will become apparent from the remaining, mentioned in the dependent claims characteristics.

The invention will be explained below in embodiments with reference to the accompanying drawings. Show it:

1 a motor vehicle with an automatic transmission and a transmission control according to the invention;

2 a shift map of a transmission control;

3 a consumption map of an internal combustion engine (diesel engine) as a function of the engine speed and the effective mean pressure;

4 a NO _x map of an internal combustion engine (diesel engine) as a function of the engine speed and the effective mean pressure;

5 the NO _X map off 4 with three exemplary points showing a permissible minimum engine speed for three different values of the conversion efficiency of the exhaust aftertreatment device and

6 a flowchart for the prediction of a transmission ratio of an automatic transmission according to the present invention.

1 shows a motor vehicle 10 that is an internal combustion engine 12 as a drive source. The internal combustion engine 12 is a predominantly lean-burn internal combustion engine, in particular a diesel engine. Alternatively, however, it may also be a gasoline engine, which is operated predominantly with a lean air-fuel mixture.

The outlets of the cylinders of the internal combustion engine 12 are with an exhaust system 14 fluidically connected. The exhaust system 14 has an exhaust manifold 16 on, which combines the exhaust gas flows of the cylinder and into an exhaust pipe 18 initiates. As in the operation of the internal combustion engine 12 With a lean air-fuel mixture unavoidable nitrogen oxides NO _{X are} generated, includes the exhaust system 14 an exhaust aftertreatment device 20 , which is designed for the conversion of nitrogen oxides. In particular, it is in the exhaust aftertreatment device 20 to a NO _x storage catalyst or an SCR catalyst. NO _x storage catalysts store nitrogen oxides of the exhaust gas in the form of a nitrate salt, as long as the NO _x storage catalyst is acted upon by a lean exhaust gas atmosphere. To regenerate the NO _x storage catalyst, it is charged with a rich exhaust gas atmosphere (λ <1), whereby the stored nitrate is released as NO ₂ and reduced to nitrogen N ₂ . Unless the internal combustion engine 12 for the purpose of NO _x regeneration of the NO _x storage catalyst 20 can not be easily operated with a rich air-fuel mixture, as is usually the case with diesel engines, must be a rich exhaust gas before the storage catalytic converter 20 be generated by other means. This can, for example, by the injection of fuel by means of an injector 22 done as in 1 is indicated. By contrast, SCR storage catalysts are able to selectively convert nitrogen oxides of the exhaust gas in the presence of a special reducing agent which is temporarily stored in the SCR catalyst. For this purpose, upstream of the SCR catalyst, an injection of a reducing agent into the exhaust gas duct takes place, which is ammonia NH ₃ or a chemical precursor compound of this, in particular urea. The one way or another cleaned exhaust gas leaves via an outlet 24 the exhaust duct 18 into the environment. Of course, the exhaust system 14 still further aftertreatment devices include, for example, particulate filter or a precatalyst, which are not shown here.

In addition, the exhaust system includes 14 Usually various sensors to detect various parameters of the exhaust gas and / or components and the internal combustion engine 12 to control. For example, lambda probes for detecting the air ratio in the exhaust duct 18 be arranged. Furthermore, in particular downstream of the catalyst 20 a NO _x sensor may be arranged, which is the monitoring of the catalyst 20 as well as an on-board diagnostic OBD thereof.

The internal combustion engine 12 is via an engine output shaft 26 with an automatic transmission 28 mechanically coupled. The gear 28 represents a gear ratio of the speed of the output shaft 26 to a rotational speed of an output shaft 30 of the transmission 28 one. In the transmission 28 It is a continuous or non-continuous, automatic transmission, such as a torque converter, a CVT (continuous variable transmission) or a dual-clutch transmission. Via a axle drive 34 is the drive torque on a drive axle 36 and its drive wheels 38 transfer.

The control of the automatic transmission 28 via a transmission control 40 , which is essentially a microcomputer, in which a control algorithm for controlling the transmission 28 in computer readable form and suitable maps, in particular one or more switching maps 42 , stored. The transmission control 40 receives various input signals, which it processes according to the stored algorithms and in dependence of which they have a gear ratio of the transmission 28 predetermined. Depending on the gear ratio thus determined, it controls the transmission 28 , in particular its switching valves, with corresponding control signals. In the case of a non-continuous automatic transmission, which has a certain number of defined gear ratios (gears), gives the transmission control 40 Upshift signals HSS for a change to a higher gear and downshift signals ASS for one Change to a lower gear to the automatic transmission 28 , as control signals off.

The input signals of the transmission control 40 include an actual vehicle speed v_Fzg or a size equivalent thereto, for example, an engine speed n_m of the internal combustion engine 12 (corresponds to the speed of the motor output shaft 26 ), a speed of the transmission output shaft 30 or a speed of the drive axle 36 , All of the above sizes can be converted into each other with simple factors. Further, the transmission control receives 40 as an input value, a value that reflects an actual vehicle load. This may, for example, be a value PWG of a pedal value transmitter, which indicates the degree of actuation of an accelerator pedal by a driver and thus reflects the driving moment desired. An equivalent quantity for this purpose is an effective mean pressure p_me of the cylinders of the internal combustion engine 12 or, if present, the opening of one in an intake tract of the internal combustion engine 12 Finally, according to a preferred embodiment of the invention, a diagnostic value OBD of an on-board diagnostic device in the transmission control 40 indicating the conversion efficiency of the catalyst 20 with regard to the conversion of an exhaust gas component, here with respect to the conversion of NO _x . Usually, the conversion efficiency of catalysts is anyway determined and monitored at regular intervals by on-board diagnostic procedures. This can be done, for example, by means of the NO _x concentration behind the catalyst 20 which is detected with the already mentioned NO _x sensor and in relation to a current (measured or map-based) NO _X -Ro emissions of the engine 12 is set. Alternatively, the transmission control 40 the conversion efficiency of the catalyst 20 also determine directly, for which also behind the catalyst 20 measured NO _x concentration can be used.

2 shows an exemplary switching map 42 as is typical in a transmission control 40 for a non-continuous automatic transmission 28 with example five gear ratios (gears) is deposited. The transmission map 42 contains for each change between two successive gear ratios each one upshift characteristic 44 and a switch-back characteristic 46 , The characteristics 44 . 46 specify the upshift and downshift points as a function of the vehicle speed v_Fzg and the pedal value PWG. For example, the 1-2 marked upshift characteristic 44 the upshift point from the first to the second gear in response to v_Fzg and PWG, the line 2-3 the upshift point from the second to the third gear, etc. The 2-1 designated downshift characteristic 46 In contrast, indicates the switch-back point of the change from the second to the first gear stage, the characteristic curve 3-2 the switch-back from the third to the second gear stage, etc. It can be seen that the switch-back 46 opposite the upshift characteristics 44 are shifted in the direction of lower vehicle speeds.

Shift maps for continuous transmissions often have no shift characteristics 44 . 46 but represent the transmission ratio continuously depending on the vehicle speed and the engine load.

The 3 and 4 show a consumption map or a NO _X map, depending on the engine speed and the effective mean pressure of the internal combustion engine. The isolines of the consumption map enter 3 the specific fuel consumption b _{e of} the internal combustion engine in g / kWh again. The NO _X map in 4 again shows the isolines for the NO _x -Ro emissions of the internal combustion engine for the various operating points in g / kWh.

With 48 is in 3 and 4 exemplified an isoline of the same power of the internal combustion engine. Furthermore, two points A and B are shown by way of example, each on the Leistungsisolinie 48 lie. In this case, point A represents a high gear of the transmission 28 (small gear ratio) and point B a small gear (high gear ratio). It is off 3 recognizable that in terms of fuel consumption is basically a lower speed (and correspondingly higher load) and thus favor higher gear ratios. At point B, fuel consumption is reduced by about 9% (or about 9% less CO ₂ emissions) compared to point A. However, this image is tarnished by the NO _x raw emission, such as 4 shows. Thus, the NO _x -Rohemission the internal combustion engine at point B by about 200% compared to point A is doubled.

The invention thus makes use of the knowledge of the NO _X catalyst -Konvertierungseffizienz 20 advantage. Unless the catalyst 20 has a high conversion efficiency, which is still able to safely convert, for example, the present at operating point B NO _x -Rohemission, so is the transmission ratio of the automatic transmission 28 adapted to the fact that small engine speeds are realized, for example, of at least 1500 min ^-1 according to point B in 4 ,

This principle is again based on 5 explains that the same NO _X map as in 4 represents. Here are again three points C, D and E on the isoline 48 same performance shown as an example. The points C, D and E are those speeds at which depending on a specific conversion efficiency of the NO _x catalyst 20 a sufficient exhaust aftertreatment can be guaranteed. Thus point C at the given load request by the driver corresponds to the isoline 48 a permissible minimum speed with a high conversion efficiency of the catalyst 20 , This is here, for example, at about 1700 min ^-1 . Point D indicates the minimum speed of about 2100 min ^-1 at an average catalyst efficiency and point E, the minimum speed at about 2,400 min ^-1 at an even lower catalyst efficiency. According to the method according to the invention, therefore, the permissible minimum speed is dependent on the determined conversion efficiency of the catalyst 20 determined. Depending on the minimum engine speed determined in this way, the transmission ratio suitable for this purpose is determined in accordance with the current vehicle speed and vehicle load.

As a result, for example, results in a plurality of switching maps 42 , such as in 2 wherein each map for a predetermined conversion efficiency of the exhaust aftertreatment device 20 or is designed for a permissible minimum engine speed. From the three in 5 Catalyst efficiencies and the three minimum speeds thus allowed would thus be three different maps 42 result. In this case, preferably a minimum engine speed after upshift at a vehicle acceleration is predetermined and a minimum engine speed before downshifting for a deceleration process. The resulting upshift characteristics 44 and switch-back characteristics 46 are increasingly shifted towards higher vehicle speeds as the conversion efficiency decreases, that is, as the conversion efficiency decreases, the upshift is progressively retarded to avoid too low engine speeds and hence excessive NO _x emissions. It is not necessary that all characteristics 44 and 46 adapted according to the conversion efficiency. In particular, those switching characteristics for ride comfort reasons remain unchanged, which characterize the change between the highest gears.

In an alternative embodiment, different switching characteristics do not become available for different conversion efficiencies 42 held, but a single switching map 42 is determined according to the observed conversion efficiency of the catalyst 20 to comply with the minimum engine speed calculated.

The course of essential steps of the method according to the invention is shown again in FIG 6 shown. Input value is the conversion efficiency of the catalyst 20 , which is preferably obtained from on-board diagnostics (OBD). Depending on this input value, the permissible minimum engine speed after upshifting n_min_H and the minimum engine speed before downshifting n_min_R are determined as output values from a NO _{x characteristic} map. Depending on the minimum engine speeds n_min_R and n_min_H, a permissible transmission ratio for the upshift i_H and for the downshift i_R is then determined.

The invention thus allows by very simple measures to influence the control program of the transmission control so that the lowest possible CO ₂ emissions (and thus lowest possible consumption) to achieve at the same time high emissions safety with respect to nitrogen oxides or other exhaust gas components.

LIST OF REFERENCE NUMBERS

10

motor vehicle

12

Internal combustion engine

14

exhaust system

16

exhaust manifold

18

exhaust duct

20

exhaust treatment device

22

injector

24

exhaust outlet

26

Motor output shaft

28

automatic transmission

30

Transmission output shaft

32

clutch

34

transaxles

36

drive axle

38

drive wheel

40

transmission control

42

Shift map

44

Upshift profile

46

Downshift characteristic curve

48

Isoline of equal power

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

• US 3895541 [0004]
• EP 1410935 A1 [0004]

Claims (10)

Method for operating an automatic transmission ( 28 ) of a motor vehicle ( 10 ), wherein a transmission ratio of the automatic transmission ( 28 ) in dependence on an operating point (n, L) of the motor vehicle ( 10 ) from a stored switching map ( 42 ) is predetermined and in dependence on the predetermined transmission ratio, a switching signal (HSS, RSS) for controlling the transmission ratio of the automatic transmission ( 38 ), characterized in that the transmission ratio of the automatic transmission ( 28 ) further in dependence on a conversion efficiency of an exhaust aftertreatment device ( 20 ) with respect to at least one exhaust gas component is predetermined. The method of claim 1, wherein the transmission ratio is predetermined so that, while maintaining a not to be exceeded concentration threshold of at least one exhaust gas component downstream of the exhaust aftertreatment device ( 20 ) a CO ₂ raw emission and / or a fuel consumption of the internal combustion engine ( 10 ) is as low as possible. Method according to one of the preceding claims, wherein depending on the conversion efficiency of the exhaust aftertreatment device ( 20 ) a minimum engine speed of the internal combustion engine ( 10 ), in which a raw emission of the exhaust gas component is still sufficiently exhausted by the exhaust gas aftertreatment device ( 20 ) is converted, and the transmission ratio as a function of the minimum engine speed of the internal combustion engine ( 10 ) is predetermined. Method according to one of claims 1 to 3, wherein for different conversion efficiencies of the exhaust gas aftertreatment device ( 20 ) each a switching map ( 42 ) is predetermined. Method according to one of claims 1 to 3, wherein a single switching map ( 42 ) is predetermined and depending on the conversion efficiency of the exhaust aftertreatment device ( 20 ) the switching map ( 42 ) is adapted. Method according to one of the preceding claims, wherein the exhaust gas component comprises nitrogen oxides (NO _x ) and exhaust aftertreatment device ( 20 ) is a catalyst for the conversion of nitrogen oxides, in particular a NO _x storage catalyst or an SCR catalyst Method according to one of the preceding claims, wherein at a high conversion efficiency of the exhaust aftertreatment device ( 20 ) a smaller gear ratio (higher gear, lower speed) is predetermined than at a lower conversion efficiency. Method according to one of the preceding claims, wherein at a high conversion efficiency of the exhaust aftertreatment device ( 20 ) compared with a lower conversion efficiency at least one switching characteristic ( 44 . 46 ) of the switching map ( 42 ) is shifted at least in sections in the direction of a lower vehicle speed (v_Fzg) or of the equivalent size and vice versa. Transmission control ( 40 ) for an automatic transmission ( 28 ) arranged to carry out the method according to one of claims 1 to 8. Motor vehicle ( 10 ) comprising an internal combustion engine ( 12 ), an automatic transmission ( 28 ) and a transmission control ( 40 ), which is set up, the automatic transmission ( 28 ) according to the method of any one of claims 1 to 8.

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