Method for operating a drive device for a motor vehicle and corresponding drive device

Abstract

Method for operating a drive device (1) for a motor vehicle, which drive device (1) has an exhaust gas-generating drive unit (2), a gear change transmission (15) connected to the drive unit (2) for setting a gear selected from a plurality of gears, and an exhaust gas aftertreatment device (12) for aftertreating the exhaust gas, characterized in that, based on at least one gear change prediction parameter of the drive device (1) and / or the motor vehicle, a gear change period is determined, after which the gear change transmission (15) is expected to be activated to change the gear, wherein, if a duration of the gear change period falls below a threshold value, an oxygen loading of an oxygen reservoir of the exhaust gas aftertreatment device (12) is set to a target oxygen loading, wherein a time period is used as the threshold value which is sufficientto adjust the oxygen loading to the target oxygen loading.

Description

[0001] The invention relates to a method for operating a drive device for a motor vehicle, which has an exhaust-generating drive unit, a gearshift transmission connected to the drive unit for setting a gear selected from several gears, and an exhaust gas aftertreatment device for aftertreating the exhaust gas. The invention further relates to a drive device for a motor vehicle.

[0002] For example, DE 10 2019 202 404 A1 is known from the prior art. This describes a method for controlling the run-out behavior of an internal combustion engine in whose exhaust pipe a three-way catalyst is arranged. The length of a run-out of the internal combustion engine is predicted, and the run-out behavior is then controlled such that the oxygen loading of the three-way catalyst at the end of the run-out is in the range of 40% to 60% of the oxygen storage capacity of the three-way catalyst.

[0003] Furthermore, US Pat. No. 9,664,592 B2 discloses various methods for operating an engine in response to transmission shifts without fuel supply. For example, one of the methods for operating the engine includes deactivating at least one engine cylinder, performing a diagnostic while the at least one engine cylinder is deactivated, and, while the engine is operating under high load, predicting a transmission shift. In response to the predicted transmission shift, an engine load is reduced and the diagnostic is terminated.

[0004] The document DE 198 58 468 A1 discloses a method for controlling the fuel supply during a deceleration cut-off mode, wherein the amount of oxygen stored in the catalyst or the temperature of the catalyst is determined and fuel is intermittently supplied to the engine so that the fuel is converted in the catalyst and reduces excess oxygen present therein.

[0005] Furthermore, the prior art includes the document DE 10 2016 102 546 A1 and the non-patent literature Konrad Reif: Exhaust gas technology for combustion engines, Wiesbaden: Springer Fachmedien, ISBN 978-3-658-09521-5.

[0006] It is an object of the invention to propose a method for operating a drive device for a motor vehicle which has advantages over known methods, in particular brings about a particularly effective reduction of pollutants in the exhaust gas generated by the drive unit.

[0007] This is achieved with a method for operating a drive device for a motor vehicle with the features of claim 1. It is provided that, based on at least one gear change prediction parameter of the drive device and / or the motor vehicle, a gear change period is determined after which the gear change transmission is expected to be activated to change the driving gear, wherein if a threshold value is undershot by a duration of the gear change period, an oxygen load of an oxygen reservoir of the exhaust gas aftertreatment device is set to a target oxygen load, wherein a time period is used as the threshold value which is sufficient to adjust the oxygen load to the target oxygen load.

[0008] Advantageous embodiments with expedient further developments of the invention are specified in the dependent claims.

[0009] The drive device serves to drive the motor vehicle, thus providing a drive torque directed toward driving the motor vehicle. To provide the drive torque, the drive device comprises the drive unit. During operation of the drive device, fuel and fresh gas are supplied to the drive unit at least temporarily, with the fresh gas at least temporarily containing fresh air. Additionally, the fresh gas may comprise exhaust gas, provided exhaust gas recirculation is implemented, in which the exhaust gas generated by the drive unit is at least partially recirculated back into the drive unit, namely as a component of the fresh gas.

[0010] The drive unit has a drive shaft that is connected to the gearshift transmission, in particular to an input shaft of the gearshift transmission. At least temporarily, the drive unit is connected to the gearshift transmission via the drive shaft, so that the drive torque provided by the drive unit is transferred to the gearshift transmission. The gearshift transmission, in turn, is connected to at least one driven wheel axle of the motor vehicle. More precisely, an output shaft of the gearshift transmission is connected to the wheel axle.

[0011] With the aid of the drive unit, at least one wheel axle can be driven, or is driven at least temporarily, via the gearshift transmission. Using the gearshift transmission, different gear ratios can be set between the drive unit and the wheel axle. To drive the motor vehicle, a gear is selected from several gears of the gearshift transmission, and the selected gear is set on the gearshift transmission. The gear ratio assigned to the gear is subsequently applied between the drive unit and the at least one wheel axle.

[0012] During operation of the drive unit, exhaust gas is generated, which is discharged to the environment outside the drive system or the motor vehicle. Since the exhaust gas generated by the drive unit contains pollutants, the exhaust gas is first fed to the exhaust aftertreatment system before being released into the environment. In the exhaust aftertreatment system, the pollutants are at least partially converted into less hazardous products. Only after passing through the exhaust aftertreatment system is the exhaust gas discharged to the environment outside.

[0013] The exhaust gas aftertreatment device is available, for example, as a vehicle catalyst, in particular as a three-way catalyst, oxidation catalyst, NO xStorage catalyst or SCR catalyst. However, it can also be designed as a particulate filter, particularly a gasoline particulate filter or a diesel particulate filter. The conversion rate and thus the conversion performance of the exhaust aftertreatment system, with which the pollutants are converted into less hazardous products, depend in particular on the temperature of the exhaust aftertreatment system and / or the oxygen load of the exhaust aftertreatment system.

[0014] Typically, the conversion rate or conversion efficiency is optimal at a specific temperature, also referred to as the operating temperature of the exhaust aftertreatment system, and / or at a specific oxygen loading, also referred to as the target oxygen loading. This conversion efficiency can also be referred to as the target conversion efficiency. At a temperature lower than the operating temperature, a lower conversion rate exists, which increases as the temperature rises toward the operating temperature. The same applies to an oxygen loading that deviates from the target oxygen loading.

[0015] In order to reduce fuel consumption of the drive device, it can be provided for the drive unit or the drive device to be operated at least temporarily in overrun mode. In overrun mode, the drive unit is drive-technically coupled to the wheel axle, but no fuel is supplied to it. At a driving speed other than zero of the motor vehicle, the wheel axle thus drags the drive unit along. As a result, fresh gas, in particular fresh air, is conveyed from the drive unit towards the exhaust gas aftertreatment device or through the exhaust gas aftertreatment device. This leads to an additional loading of the exhaust gas aftertreatment device or its oxygen storage device with oxygen, such that the oxygen loading of the exhaust gas aftertreatment device deviates from the target oxygen loading, in particular towards higher values.

[0016] During a gear change, the drive unit is operated with fuel, at least briefly, to provide the drive torque; in other words, fuel is supplied to it. The drive torque provided by the drive unit is preferably used to align the rotational speeds of shafts of the drive device, in particular of the drive unit and the gearshift transmission, preferably to align the rotational speed of the drive shaft of the drive unit with the rotational speed of the input shaft of the gearshift transmission.

[0017] This ensures a high level of driving comfort for the vehicle's user and / or a rapid gear change during gear changes. If this gear change occurs while the drive unit is coasting, the drive unit was operating without fuel before the gear change, meaning that the exhaust gas aftertreatment system may have an oxygen load that deviates from the target oxygen load. Accordingly, the exhaust gas generated by the drive unit can only be cleaned of pollutants with reduced effectiveness.

[0018] For this reason, the invention provides for determining the gear change period. The gear change period describes the period after which the gear change transmission is expected to be activated to change the gear. In other words, the gear change period is the period that begins at the current time and ends with the gear change, or immediately after the end of which the gear change is expected to occur. Alternatively, the time after which the next gear change is expected to occur can also be determined. This time is in turn compared with the threshold value, and if the time falls below the threshold value, the described measures are taken.

[0019] The gear change period is determined from the at least one gear change prediction parameter. The gear change prediction parameter makes it possible to estimate at which point in the future the gear change will be performed with a certain probability. For example, the driving speed of the motor vehicle, a rotational speed of the drive unit, or the like can be used as the gear change prediction parameter. After determining the gear change period, this period, or its duration, is compared with the threshold value.

[0020] If the gear change period or its duration falls below the threshold value, i.e. if the gear change period or its duration is shorter than the threshold value, measures are taken to enable sufficient conversion of the pollutants contained in the exhaust gas. These measures include adjusting the oxygen loading of the oxygen storage device to the target oxygen loading or at least towards the target oxygen loading. The threshold value describes a period of time that is sufficient to adjust the oxygen loading to the target oxygen loading. For example, the threshold value is fixed and constant. In this case, it is selected in such a way that the oxygen loading is adjusted to the target oxygen loading under all ambient conditions and / or operating conditions of the drive system.

[0021] Of course, it is particularly advantageous to select the threshold value depending on at least one ambient condition and / or at least one operating condition. The ambient condition is understood to mean, for example, an ambient temperature, an ambient air pressure, or the like. The operating condition is, for example, the drive torque currently provided by the drive unit, its speed, its drive power, an exhaust gas flow rate through the exhaust aftertreatment device, or the like.

[0022] The described procedure enables the exhaust aftertreatment system to be prepared for operation of the drive unit during gear changes. This allows the exhaust gases of the drive unit to be reliably freed of pollutants, at least temporarily and at least partially, even during such operation. Overall, this results in a significant reduction in pollutant emissions from the drive system.

[0023] A further development of the invention provides that the gear change period is determined only during overrun operation of the drive device. Overrun operation means that the drive unit or its drive shaft is coupled, preferably rigidly, to the at least one driven wheel axle of the motor vehicle. At a driving speed of the motor vehicle other than zero, the drive unit is towed by the wheel axle, while simultaneously interrupting the fuel supply to the drive unit. The drive unit is thus operated without fuel.Since the deviation of the oxygen load from the target oxygen load occurs particularly during overrun, the determination of the gear shift period, the comparison of the duration of the gear shift period with the threshold value, and, if necessary, the adjustment of the oxygen load to the target oxygen load should only be performed during overrun, i.e., only when actually necessary. This improves the efficiency of the drive system.

[0024] A further development of the invention provides that during the gear change, the drive unit is operated to provide a drive torque that is used to synchronize the gearshift transmission. Synchronization refers to the aforementioned matching of the rotational speeds of the shafts of the drive device or the gearshift transmission. With the aid of the drive torque, which is different from zero, one of the shafts is accelerated or decelerated, so that its rotational speed changes toward the rotational speed of another of the shafts, in particular to this rotational speed. This significantly accelerates the gear change.

[0025] A further development of the invention provides that at least 20% and at most 70% of the oxygen storage capacity of the oxygen storage is used as the target oxygen loading. The conversion rate of the exhaust gas aftertreatment device is at its maximum between 30% and 50% (including these values). In order to achieve sufficient conversion of the pollutants, the oxygen loading achieved during the adjustment of the oxygen loading should therefore be between 20% and 70% (again, these values ​​are included). Accordingly, the oxygen loading is selected such that it is at least 20%, at least 30%, at least 40%, and / or at most 70%, at most 60%, or at most 50%, in each case based on the total oxygen storage capacity of the oxygen storage. This achieves high efficiency in the conversion of the pollutants.

[0026] A further development of the invention provides that at least one of the following parameters is used as a gear change prediction parameter: drive program, driving speed, brake pressure, brake input, transmission input speed, wheel speed gradient, and road gradient. The drive program specifically describes speed limits at which the current gear is shifted to a next higher gear or a next lower gear. The drive program can be used to determine whether the motor vehicle should be operated in a more sporty or more efficient manner.

[0027] The driving speed describes the current speed of the motor vehicle, particularly in the main direction of travel. The brake pressure describes the pressure currently applied to the motor vehicle's service brake. Instead of the brake pressure, for example, a braking force acting on the motor vehicle can also be used. The braking command is understood to be a command by the motor vehicle user regarding the braking of the motor vehicle. For example, the braking command is the position of a control element of the motor vehicle, particularly a brake pedal.

[0028] The transmission input speed describes the speed of an input shaft of the gearshift transmission, which is drive-connected to the drive unit or its drive shaft, preferably via a clutch. The wheel speed gradient describes the gradient of the wheel speed or the wheel speed of a wheel of the motor vehicle over time. The wheel is preferably assigned to the driven wheel axle of the motor vehicle and is drive-connected to the drive unit accordingly. The ground inclination is the inclination of the ground on which the motor vehicle is located or supported. Based on the ground inclination, it can be determined whether a horizontal force resulting from the vehicle's own weight is different from zero and whether it is directed towards accelerating or decelerating the vehicle.

[0029] At least one of the aforementioned parameters is used as a gear change prediction parameter. However, it is particularly preferred to use several of the aforementioned parameters, so that the gear change period is determined based on several gear change prediction parameters. It is particularly preferred to determine the gear change period based on all of the aforementioned parameters. This achieves a particularly high degree of accuracy for the gear change period. Determining the gear change period from one of the described parameters enables a precise estimation of when the gear change can be expected. Accordingly, the exhaust gas aftertreatment system can be prepared for the operation of the drive unit in a highly targeted and highly efficient manner.

[0030] A further development of the invention provides that adjusting the oxygen loading comprises at least one of the following measures: introducing fuel into the drive unit when the drive unit is operating without fuel, introducing fuel into the drive unit when the drive unit is operating with fuel, and introducing fuel vapor from a fuel tank into the exhaust gas aftertreatment device. Each of the aforementioned measures is suitable for adjusting the oxygen loading toward the target oxygen loading and thus increasing the conversion efficiency of the exhaust gas aftertreatment device toward the specific conversion efficiency or the target conversion efficiency.

[0031] Unfired operation of the drive unit means that it is operated in such a way that no fuel is burned. Nevertheless, fuel is introduced into the drive unit in order to change the oxygen load towards the target oxygen load. The fuel introduced into the drive unit passes through the drive unit and is discharged together with the exhaust gas towards the exhaust aftertreatment device. With this procedure, the fuel burns downstream of the drive unit, in particular upstream of the exhaust aftertreatment device or in the exhaust aftertreatment device. This procedure has the advantage that the drive torque of the drive unit does not change, in particular that the drag torque of the drive unit remains unchanged, regardless of whether fuel is introduced into the drive unit or not.

[0032] Fired operation of the drive unit means that fuel is supplied to the drive unit, or more fuel than is normally required to provide the drive torque. In this respect, it is particularly intended to supply fuel to the drive unit at least temporarily during overrun operation and to burn this fuel in the drive unit. Additionally or alternatively, fuel vapor from the fuel tank is introduced into the exhaust gas aftertreatment system. Fuel vapor is understood to mean, in particular, evaporated fuel. This is usually present in addition to the liquid fuel in the fuel tank and can be used to adjust the oxygen loading towards the target oxygen loading.

[0033] A further development of the invention provides that, during fired operation of the drive unit, an ignition angle is set such that the actual torque provided by the drive unit continues to correspond to a target torque. The actual torque is understood to mean the drive torque currently provided by the drive unit. The drive unit is operated such that the actual torque corresponds to the target torque; preferably, the actual torque is regulated to the target torque.

[0034] During overrun of the drive system, the target torque has a specific value, in particular, it is less than zero, thus having a braking effect on the motor vehicle. If the drive unit is operated with the engine running during overrun, the actual torque changes toward larger values. To prevent this, the ignition angle is changed so that the actual torque continues to correspond to the target torque, with the target torque preferably remaining unchanged. This reliably prevents any impairment of the motor vehicle's driving comfort.

[0035] A further development of the invention provides that the introduction of fuel vapor into the exhaust aftertreatment device occurs by opening a tank venting valve fluidically arranged between the fuel tank and the exhaust aftertreatment device. The fuel tank is, in particular, a pressurized tank; during operation of the drive system, the pressure in it is greater than ambient pressure. The tank venting valve is fluidically arranged between the fuel tank and the exhaust aftertreatment device.

[0036] In particular, the tank vent valve is fluidically located between the fuel tank and the drive unit, so that it is fluidically connected to the exhaust aftertreatment system via the drive unit.

[0037] When the tank vent valve is closed, pressure equalization between the fuel tank and the outside environment is prevented, so that overpressure exists or can exist in the fuel tank, at least temporarily. When the tank vent valve is open, fuel vapor flows from the fuel tank toward the drive unit and via this to the exhaust aftertreatment system. Thus, by opening the tank vent valve, the oxygen loading can be adjusted toward the target oxygen loading.

[0038] A further development of the invention provides that a fuel vapor accumulator is arranged fluidically between the fuel tank and the outside environment, and that the fuel vapor is introduced into the exhaust aftertreatment device by purging the fuel vapor accumulator. The fuel vapor accumulator serves to temporarily store gaseous fuel, particularly during venting of the fuel tank toward the outside environment. The fuel vapor accumulator prevents gaseous fuel from escaping from the fuel tank into the outside environment.

[0039] Since the storage capacity of the fuel vapor accumulator is limited, it must be regenerated or purged from time to time. This is achieved by passing air from the outside environment through the fuel vapor accumulator. The air absorbs the fuel vapor stored in the fuel vapor accumulator. The air, enriched with fuel vapor in this way, is fed to the exhaust gas aftertreatment system, in particular via the tank venting valve. In this way, the intermediate fuel vapor storage serves to adjust the oxygen loading toward the target oxygen loading. This procedure reduces the fuel required to condition the exhaust gas aftertreatment system.

[0040] The invention further relates to a drive device for a motor vehicle, in particular for carrying out the method according to the embodiments in the context of this description, wherein the drive device has a drive unit generating exhaust gas, a gear change transmission connected to the drive unit for setting a driving gear selected from several driving gears, and an exhaust gas aftertreatment device for aftertreating the exhaust gas.The drive device is provided and designed to determine, based on at least one gear change prediction parameter of the drive device and / or the motor vehicle, a gear change period after which the gear change transmission is expected to be activated to change the driving gear, wherein if a duration of the gear change period falls below a threshold value, an oxygen load of an oxygen storage device of the exhaust gas aftertreatment device is set to a target oxygen load, wherein a time period is used as the threshold value which is sufficient to adjust the oxygen load to the target oxygen load.

[0041] The advantages of such a design of the drive device or such a procedure have already been pointed out. Both the drive device and the method for its operation can be further developed according to the explanations in this description, so reference is made to these in this regard.

[0042] The features and feature combinations described in the description, in particular the features and feature combinations described in the following description of the figures and / or shown in the figures, can be used not only in the respective combination specified, but also in other combinations or on their own, without departing from the scope of the invention. Thus, embodiments are also considered to be encompassed by the invention that are not explicitly shown or explained in the description and / or the figures, but which follow from or can be derived from the explained embodiments.

[0043] The invention will be explained in more detail below with reference to the exemplary embodiments shown in the drawings, without limiting the invention. Fig. 1 a schematic representation of a drive device for a motor vehicle.

[0044] The Fig. 1 shows a schematic representation of a drive device 1 comprising a drive unit 2, which here is in the form of an internal combustion engine, and an exhaust tract 3. In the illustrated embodiment, the drive unit 2 has a plurality of cylinders, each with a combustion chamber 4. Each of the cylinders has at least one intake valve 5 and at least one exhaust valve 6. Fresh gas from a fresh gas tract 7 can be supplied to the respective cylinder via each of the intake valves 5, whereas exhaust gas from the corresponding cylinder can escape through each of the exhaust valves 6, namely in the direction of the exhaust tract 3.

[0045] The fresh gas is supplied to the intake valves 5 by a compressor 8, which is part of an exhaust gas turbocharger 9. In addition to the compressor 8, the exhaust gas turbocharger 9 has a turbine 10, which is fluidly connected to the exhaust valves 6 via an exhaust line 11, which is part of the exhaust tract 3. Downstream of the turbine 10 is an exhaust gas aftertreatment device 12. Downstream of the exhaust gas aftertreatment device 12, the exhaust tract 3 opens into an external environment of the drive device 1, for example, via a tailpipe. It should be noted that the exhaust gas turbocharger 9 is purely optional. It can also be omitted accordingly.

[0046] The drive unit 2 has a drive shaft 14. This is drive-connected to an input shaft of a gearshift transmission 15. On the side of the gearshift transmission 15 that is drive-facing away from the input shaft or drive shaft 14, the gearshift transmission 15 has an output shaft 16. The output shaft 16 is connected to a wheel axle (not shown here) of the motor vehicle. The gearshift transmission 15 is provided and designed to set different gear ratios between its input shaft and the output shaft 16. Accordingly, during operation of the drive device 1, a gear is selected from the multiple gears of the gearshift transmission 15 and set thereon.

[0047] In particular, during overrun operation of the drive device 1, it is provided to determine a gear change period. This is done using at least one gear change prediction parameter. The gear change period describes the time period after which the gear selected on the gear change transmission 15 is expected to be changed in order to achieve a different gear ratio. If the gear change period or its duration falls below a certain threshold value, the exhaust gas aftertreatment device 12 or an oxygen reservoir thereof is conditioned.

[0048] Conditioning is performed by adjusting the oxygen loading of the oxygen storage to a target oxygen loading. This is performed, in particular, preferably only when the oxygen loading is greater than the target oxygen loading. If the duration of the gear shift period is greater than the threshold value, the conditioning measure is not activated; in particular, the conditioning measure in the form of adjusting the oxygen loading to the target oxygen loading remains deactivated.

[0049] The described procedure for operating the drive system 1 enables supportive operation of the drive unit 1 during gear changes using the drive unit 2 with low pollutant emissions. This is achieved by predictively preparing the exhaust gas aftertreatment system 12 for the operation of the drive unit 2 during gear changes, namely by adjusting the oxygen loading to the target oxygen loading. Ultimately, the pollutant emissions of the drive system 1 are thus significantly reduced. LIST OF REFERENCE SYMBOLS: 1 drive device 2 drive unit 3 Exhaust system 4 combustion chamber 5 Inlet valve 6 exhaust valve 7 Fresh gas tract 8 compressors 9 exhaust gas turbocharger 10 turbines 11 Exhaust pipe 12 Exhaust aftertreatment system 14 Drive shaft 15 gearshift gearboxes 16 Output shaft

Claims

[1] Method for operating a drive device (1) for a motor vehicle, which has a drive unit (2) generating exhaust gas, a gear change transmission (15) connected to the drive unit (2) for setting a gear selected from several gears, and an exhaust gas aftertreatment device (12) for aftertreating the exhaust gas, characterized bythat a gear change period is determined based on at least one gear change prediction parameter of the drive device (1) and / or the motor vehicle, after which the gear change transmission (15) is expected to be activated to change the driving gear, wherein if a duration of the gear change period falls below a threshold value, an oxygen load of an oxygen reservoir of the exhaust gas aftertreatment device (12) is set to a target oxygen load, wherein a time period is used as the threshold value which is sufficient to adjust the oxygen load to the target oxygen load. [2] Method according to claim 1, characterized by that the gear change period is determined only during overrun operation of the drive device (1). [3] Method according to one of the preceding claims, characterized bythat during the gear change the drive unit (2) is operated to provide a drive torque which is used to synchronize the gear change transmission (15). [4] Method according to one of the preceding claims, characterized by that at least 20% and at most 70% of the oxygen capacity of the oxygen storage is used as the target oxygen load. [5] Method according to one of the preceding claims, characterized by that at least one of the following parameters is used as gear change prediction parameters: driving program, driving speed, brake pressure, brake input, transmission input speed, wheel speed gradient and surface inclination. [6] Method according to one of the preceding claims, characterized bythat the adjustment of the oxygen loading comprises at least one of the following measures: introducing fuel into the drive unit (2) when the drive unit (2) is operating without fuel, introducing fuel into the drive unit (2) when the drive unit (2) is operating with fuel, and introducing fuel vapor from a fuel tank into the exhaust gas aftertreatment device (12). [7] Method according to claim 6, characterized by that during the fired operation of the drive unit (2) an ignition angle is set such that an actual torque provided by the drive unit (2) continues to correspond to a target torque. [8] Method according to claim 6, characterized by that the introduction of the fuel vapor into the exhaust gas aftertreatment device (12) takes place by opening a tank venting valve arranged fluidically between the fuel tank and the exhaust gas aftertreatment device (12). [9] Method according to claim 6 or 8, characterized by that a fuel vapor accumulator is arranged fluidically between the fuel tank and an external environment and that the fuel vapor is introduced into the exhaust gas aftertreatment device (12) by flushing the fuel vapor accumulator. [10] Drive device (1) for a motor vehicle for carrying out the method according to one or more of the preceding claims, wherein the drive device (1) has a drive unit (2) generating exhaust gas, a gear change transmission (15) connected to the drive unit (2) for setting a gear selected from a plurality of gears, and an exhaust gas aftertreatment device (12) for aftertreating the exhaust gas, characterized byin that the drive device (1) is provided and designed to determine, on the basis of at least one gear change prediction parameter of the drive device (1) and / or the motor vehicle, a gear change period after which the gear change transmission (15) is expected to be activated to change the driving gear, wherein if a duration of the gear change period falls below a threshold value, an oxygen load of an oxygen reservoir of the exhaust gas aftertreatment device (12) is set to a target oxygen load, wherein a time period is used as the threshold value which is sufficient to adjust the oxygen load to the target oxygen load.

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