Method for operating a motor vehicle power plant provided with an air-fuel ratio control system, and

Abstract

The invention relates to a method for operating a power plant for a motor vehicle, the power plant having a power unit that generates exhaust gas, fuel being fed into a combustion chamber of the power unit at least temporarily depending on at least one injection parameter in order to form a fuel-fresh gas mixture, and the fuel-fresh gas mixture being fed into the combustion chamber of the power unit. According to the invention, an actual combustion air ratio is determined on the basis of the remaining oxygen content in the exhaust gas measured by means of an oxygen sensor, and the actual combustion air ratio is adjusted to a theoretical combustion air ratio by adjusting the composition of the fuel-fresh gas mixture by means of an air-fuel ratio adjustment. According to the invention, starting from a change in at least one injection parameter, an amplification factor of at least one control element for air-fuel ratio adjustment is increased from a first value to a second value in order to quickly adapt the actual combustion air ratio to the target combustion air ratio.

Description

Field of the Invention

[0001] The present invention relates to a method for operating a power unit for a motor vehicle, the power unit having a power unit that generates exhaust gas, wherein fuel is introduced into the combustion chamber of the power unit at least temporarily according to at least one injection parameter to form a fuel fresh gas mixture, wherein the actual combustion air ratio is determined according to the residual oxygen content in the exhaust gas measured by means of an oxygen sensor, and the composition of the fuel fresh gas mixture is adjusted by means of air-fuel ratio regulation to adjust the actual combustion air ratio to the theoretical combustion air ratio. In addition, the present invention relates to a power unit for a motor vehicle. Background Art

[0002] For example, the prior art known published document DE 10 2011 085 115 A1 is known. This published document describes a method for adjusting the air-fuel ratio regulation of an internal combustion engine, the internal combustion engine having an exhaust gas detector arranged in the exhaust gas passage of the internal combustion engine as part of an exhaust gas monitoring system, wherein the adjustment is carried out by comparing an analog signal with a signal measured after a preset change in the fuel-air ratio of the air-fuel mixture supplied to the internal combustion engine, and wherein the measured signal is the actual value of the output signal of the exhaust gas detector, and the analog signal is a model value derived from the air-fuel mixture supplied to the internal combustion engine by applying an exhaust gas model. It is stipulated herein that the air-fuel ratio regulator parameters of the air-fuel ratio regulation are adjusted step by step, and the difference between the maximum slope of the measured air-fuel ratio value and the maximum slope of the air-fuel ratio value expected according to the model is used as a quality criterion. Summary of the Invention

[0003] The object of the present invention is to provide a method for operating a power unit for a motor vehicle, which has advantages compared with known methods, in particular, can quickly correct the deviation between the actual combustion air ratio and the theoretical combustion air ratio.

[0004] According to the present invention, this object is achieved by a method for operating a power unit for a motor vehicle having the features described in claim 1. It is stipulated herein that starting from a change in at least one injection parameter, the amplification factor of at least one control element of the air-fuel ratio regulation is increased from a first value to a second value in order to quickly adapt the actual combustion air ratio to the theoretical combustion air ratio.

[0005] Advantageous design solutions with suitable improvements of the present invention are given in the dependent claims. It should be noted that the embodiments described in the specification are not restrictive; on the contrary, any variations of the features disclosed in the specification, claims and drawings can be implemented.

[0006] The power unit is used to drive a motor vehicle, i.e., in this context, to provide a drive torque for driving the motor vehicle. To provide the drive torque, the power unit has a power unit. During operation of the power unit, fuel and fresh gas are at least temporarily supplied to the power unit, where the fresh gas at least temporarily contains fresh air. Additionally, if exhaust gas recirculation is implemented, the fresh gas can contain exhaust gas, in which at least part of the exhaust gas generated by the power unit is guided back to the power unit again, i.e., as a component of the fresh gas. The fuel and fresh gas supplied to the power unit form a fuel-fresh gas mixture with a specific composition that is supplied to the power unit for reaction.

[0007] During operation of the power unit, due to the chemical reaction between the fuel and the fresh gas, exhaust gas is generated, and this exhaust gas is discharged in the direction of the external environment of the power unit, i.e., the motor vehicle. Since the exhaust gas generated by the power unit contains harmful substances, it is preferably first supplied to an exhaust gas aftertreatment device before being discharged into the external environment. In the exhaust gas aftertreatment device, at least part of the harmful substances are converted into less harmful products. Only after passing through the exhaust gas aftertreatment device is the exhaust gas discharged into the external environment.

[0008] For example, the exhaust gas aftertreatment device exists as a vehicle catalytic converter, especially as a three-way catalytic converter, an oxidation catalytic converter, a NO X storage catalytic converter or an SCR catalytic converter. However, the exhaust gas aftertreatment device can also be designed as a particulate filter, especially a gasoline particulate filter or a diesel particulate filter, preferably with an integrated vehicle catalytic converter, for example with a catalytic coating. The conversion rate of the exhaust gas aftertreatment device for converting harmful substances into less harmful products and thus the conversion performance depends especially on the exhaust gas composition supplied to the exhaust gas aftertreatment device and / or the storage load of the exhaust gas aftertreatment device, and the storage load is in turn related to the exhaust gas composition. Preferably, the storage load should be understood as the oxygen loading of the exhaust gas aftertreatment device, i.e., the amount of oxygen temporarily stored in the exhaust gas aftertreatment device.

[0009] To form the fuel-fresh gas mixture, i.e., to form the fuel-fresh gas mixture in the combustion chamber of the power unit, fuel is at least temporarily input into the combustion chamber. This is carried out according to at least one injection parameter. In principle, the fuel can be input into the combustion chamber in any way. For example, the fuel is directly input, especially injected, into the combustion chamber. For this purpose, the injection valve / fuel injection valve is directly connected to the combustion chamber in terms of fluid technology or even extends into the combustion chamber. In this case of direct injection, the fuel mixes with the fresh gas only in the combustion chamber. Additionally or alternatively, the fuel and the fresh gas are brought together outside the combustion chamber and are supplied to the combustion chamber together with the fresh gas, i.e., already in the form of a fuel-fresh gas mixture. This can be carried out, for example, in the form of intake manifold injection.

[0010] The combustion chamber is located in the cylinder of the power unit and is jointly delimited by the cylinder wall of the cylinder, the cylinder head of the cylinder, and the piston movably arranged in the cylinder. Preferably, the power unit has a plurality of cylinders and accordingly a plurality of combustion chambers. If the combustion chamber is mentioned within the scope of the description, the embodiments are also applicable to the design of a power unit having a plurality of combustion chambers. In particular, these embodiments are applicable to each of the combustion chambers.

[0011] The exhaust gas generated when the fuel fresh gas mixture reacts in the combustion chamber is discharged from the combustion chamber. The residual oxygen content in the exhaust gas is measured downstream of the power unit by means of an oxygen sensor. The actual combustion air ratio is determined from the residual oxygen content and compared with the theoretical combustion air ratio. If there is a deviation between the actual combustion air ratio and the theoretical combustion air ratio, the composition of the fuel fresh gas mixture is adjusted, i.e., such that the actual combustion air ratio changes in the direction of the theoretical combustion air ratio, in particular until the theoretical combustion air ratio.

[0012] This adjustment of the composition is accomplished by means of air-fuel ratio regulation. In this regard, the actual combustion air ratio or the difference between the theoretical combustion air ratio and the actual combustion air ratio is used as the control parameter for the air-fuel ratio regulation. Conversely, the composition of the fuel fresh gas mixture is the regulated variable of the air-fuel ratio regulation. Preferably, the air-fuel ratio regulation is based on PID control. Short-term deviations (with a duration in the range of seconds) in the composition of the fuel fresh gas mixture must be compensated for by the integral part. The controller must meet the stability criteria, so that the parameterization of the integral component is always a compromise between stability and spontaneity. Since the quality of the air-fuel ratio regulation is crucial for the conversion performance of the exhaust gas aftertreatment device, it has a significant impact on the emissions or harmful substances finally emitted into the external environment.

[0013] When the injection parameters on which the fuel input into the combustion chamber is based change, short-term changes in the actual combustion air ratio may occur, even if such changes are not intentional. For example, when the number of injection pulses changes, it causes a sudden change in the actual combustion air ratio, i.e., due to the spontaneous change of the fuel fresh gas mixture participating in the chemical reaction in the combustion chamber. The reason for the spontaneous change is that the conditions are different when different injection parameter values are applied. Although the proportional part of the air-fuel ratio regulation responds relatively quickly, it cannot reduce the persistent control deviation precisely enough. Nor can the derivative part, because the derivative part basically acts as a damping / attenuating effect. In addition, for stability reasons, the manifestation form of the derivative part is also severely restricted.

[0014] For this reason, at least one control element for the air-fuel ratio regulation should be adjusted such that it corrects as quickly as possible a change in the actual combustion air ratio caused by a change in at least one injection parameter. This is achieved by increasing the amplification factor of the control element from a first value to a second value. To achieve a rapid response of the air-fuel ratio regulation to a change in the actual combustion air ratio, the amplification factor is increased directly when the actual combustion air ratio changes or immediately after its change. That is, the change in the amplification factor does not start when a deviation occurs between the actual combustion air ratio and the theoretical combustion air ratio, but rather before the actual combustion air ratio deviates from the theoretical combustion air ratio due to a change in at least one injection parameter, and more precisely, before the deviation between the actual combustion air ratio and the theoretical combustion air ratio changes, in particular increases, due to a change in at least one injection parameter. The described approach enables the air-fuel ratio regulation to respond extremely rapidly to deviations and thus enables a reliable and rapid adjustment of the actual combustion air ratio to the theoretical combustion air ratio.

[0015] An improved embodiment of the invention provides that, in a first operating mode, the amplification factor is increased starting from a change in at least one injection parameter, and in a second operating mode, the increase in the amplification factor is prohibited. In other words, the increase is only carried out in the first operating mode. In contrast, in the second operating mode, the amplification factor is always constant or always selected to be the same. Preferably, the power unit is operated in the first operating mode as long as the temperature is within a specific temperature range. In contrast, if the temperature is above this temperature range, the power unit is operated in the second operating mode.

[0016] Particularly preferably, the power unit is operated in the first operating mode as long as the temperature is below a temperature threshold. If the temperature is equal to or higher than this temperature threshold, the power unit is operated in the second operating mode. For example, as the temperature, the unit temperature of the power unit (also referred to as the engine temperature) or the catalytic converter temperature is used. Thus, an adjustment of the amplification factor as required is achieved.

[0017] Additionally or alternatively, it is provided that the second value is selected according to the temperature. In particular, the lower the temperature, the larger the second value selected, and vice versa. This means that the amplification factor is increased more strongly at lower temperatures than at higher temperatures.

[0018] An improved embodiment of the present invention provides that, as at least one injection parameter, one of the following parameters is used: the number of injection pulses per working cycle, the injection location, the injection speed, and the injection duration. An injection pulse shall be understood as the input of fuel into the combustion chamber once. A working cycle includes all the power strokes of the power unit for the combustion chamber, that is, the working cycle especially starts from the intake stroke, passes through the compression stroke and the power stroke until the exhaust stroke ends. If fuel is injected into the combustion chamber more than once during the working cycle, that is, the number of injection pulses is greater than one, then the fuel input is carried out separately for each of the injection pulses, that is, separately in time from the other injection pulses. In this regard, fuel is re-input only after the end of the fuel input during one injection pulse of the injection pulses. For example, at least one pre-injection and one main injection are achieved in this way.

[0019] The injection location is understood as the part where fuel is injected. For example, the injection location can directly be the combustion chamber, but alternatively can be the intake manifold arranged upstream of the combustion chamber. For example, the injection speed describes the throughput / flow rate of the fuel input, that is, especially describes the mass flow rate or volume flow rate of the fuel during input. The injection duration is again the time period during which fuel is input into the combustion chamber. The said parameters cause a change in the actual combustion air ratio, because even if the amount of fuel per working cycle is the same, the time course of the input and thus the course of the chemical reaction will change.

[0020] An improved embodiment of the present invention provides that the amplification factor is increased especially only if the fuel fraction in the fuel fresh gas mixture composition changes by at least 10%, at least 20% or at least 30% due to a change in at least one injection parameter. A significant change in the amount of fuel input into the combustion chamber also causes a change in the actual combustion air ratio, and this change should be corrected quickly. For this reason, preferably, especially if the fuel fraction has changed by the said amount, for example, from the previous working cycle to the current working cycle, the described practice is also used. Thus, the actual combustion air ratio can be quickly adjusted to the theoretical combustion air ratio.

[0021] An improved embodiment of the present invention provides that the second value is selected to be at least 5 times, at least 7.5 times or at least 10 times the first value. In order to quickly adapt the actual combustion air ratio to the theoretical combustion air ratio, the amplification factor is significantly increased. Preferably here, the second value is one of the said multiples of the first value, where the second value is obtained by multiplying the multiple by the first value. Thus, a deviation caused by a change in at least one injection parameter can be quickly corrected.

[0022] An improved embodiment of the present invention provides that an integral control element is used as at least one control element. The integral control element can also be referred to as an I control element or an I element. The integral control element is generally very suitable for reducing the deviation between the actual combustion air ratio and the theoretical combustion air ratio in the long term. However, the integral regulating element designed for a long-term and stable air-fuel ratio regulation requires a relatively long time to achieve this purpose. For this reason, the amplification factor is increased from a first value to a second value to accelerate the correction speed.

[0023] Preferably, the first value of the amplification factor is selected such that the air-fuel ratio regulation is always stable under the normal operating conditions of the power plant and under normal boundary conditions. In contrast, the second value is much larger. In particular, the second value is selected such that the air-fuel ratio regulation is unstable when the second value of the amplification factor is continuously used, that is, it can no longer operate stably. In order to quickly correct the deviation, the short-term instability of the air-fuel ratio regulation can be accepted, and the advantages described above can be achieved thereby.

[0024] An improved embodiment of the present invention provides that the amplification factors of other control elements of the air-fuel ratio regulation are kept constant. In addition to the at least one control element, the air-fuel ratio regulation has at least one additional control element, and the additional control element is also assigned an amplification factor. Preferably, there are a plurality of additional control elements and correspondingly many amplification factors. The amplification factor of one additional control element or the amplification factors of a plurality of additional control elements are kept constant, that is, they are not increased or otherwise changed like the amplification factor of the at least one control element. Therefore, the stability of the air-fuel ratio regulation is at least temporarily and at least partially ensured.

[0025] An improved embodiment of the present invention provides that the increase in the amplification factor is cancelled after a specific period of time. That is, at the beginning of the specific period of time, with the change of at least one injection parameter, the amplification factor is set from the first value to the second value. At the end of the specific period of time, the amplification factor is set from the second value to the first value again, and the air-fuel ratio regulation is continuously operated with the amplification factor corresponding to the first value, especially until at least one injection parameter changes again. Therefore, the air-fuel ratio regulation is kept continuously stable, but the deviation of the actual combustion air ratio can still be quickly corrected.

[0026] An improved embodiment of the present invention provides that the length of the time period is determined according to at least one of the following parameters: the exhaust gas delivery time from the power unit to the oxygen sensor, the load of the power unit, the rotational speed of the power unit, the torque provided by the power unit, the temperature, in particular the exhaust gas temperature and / or the temperature of the exhaust gas aftertreatment device, and the response time of the oxygen sensor. The exhaust gas delivery time corresponds to the time required for the exhaust gas generated in the combustion chamber to flow from the power unit to the oxygen sensor. Therefore, after the end of the exhaust gas delivery time, the change in at least one injection parameter will only become apparent at the oxygen sensor and / or in the actual combustion air ratio.

[0027] Additionally or alternatively, the load, rotational speed, and torque of the power unit can also be used to determine the length of the time period. The same applies to temperature. Here, as the temperature, for example, the exhaust gas temperature of the exhaust gas or the temperature of the exhaust gas aftertreatment device is used. The response time of the oxygen sensor can also be referred to as the reaction time. This response time describes the time required for the oxygen sensor to respond to a change in at least one injection parameter after the exhaust gas packet reaches the oxygen sensor. As the response time, for example, the T90 response time is used, that is, especially in the case of a sudden change, the time length required for the oxygen sensor to reach 90% of its final value at its output.

[0028] It can be provided that the length of the time period is determined according to one of these parameters. Preferably, however, multiple or even all of these parameters are used. For example, the length of the time period is at most corresponding to the exhaust gas delivery time multiplied by a specific coefficient, which coefficient is, for example, on the one hand at least 1.0 or greater than 1.0, and on the other hand at most 3.0 or at most 2.0 or at most 1.5. The length of the time period selected in this way enables stable execution of the air-fuel ratio regulation.

[0029] An improved embodiment of the present invention provides that the length of the time period is selected such that the increase in the amplification factor terminates immediately at the latest after the change in the residual oxygen content caused by the change in at least one injection parameter has ended in the direction determined by this change. The change in the injection parameter directly causes a change in the residual oxygen content or the actual combustion air ratio in a specific direction, which direction depends on the change in the injection parameter.

[0030] In other words, the actual combustion air ratio changes in a specific direction due to changes in the injection parameters, for example, in the direction of a smaller value or a larger value. The condition for the end of this change is that the residual oxygen content or the actual combustion air ratio starts to change in another direction again due to the air-fuel ratio adjustment. For the control deviation between the theoretical combustion air ratio and the actual combustion air ratio, this means that the end of this change occurs when the control deviation is the largest, that is, at the control deviation point from which the previously continuously increasing change starts to decrease again. It is stipulated that the said time period ends at the latest with the end of this change, and preferably ends in advance. This means that the increase in the amplification factor is restored or cancelled at the latest when the change in the residual oxygen content ends. Thereby, the stability of the air-fuel ratio adjustment is ensured.

[0031] Furthermore, the present invention relates to a power unit for a motor vehicle, in particular a power unit for carrying out the method according to the embodiments within the scope of the present application, wherein the power unit has a power unit that generates exhaust gas, and fuel is input into the combustion chamber of the power unit at least temporarily according to at least one injection parameter to form a fuel fresh gas mixture, wherein the actual combustion air ratio is determined according to the residual oxygen content in the exhaust gas measured by means of an oxygen sensor, and the composition of the fuel fresh gas mixture is adjusted by means of air-fuel ratio adjustment to adjust the actual combustion air ratio to the theoretical combustion air ratio. Here, the power unit is arranged and designed such that starting from a change in at least one injection parameter, the amplification factor of at least one control element of the air-fuel ratio adjustment is increased from a first value to a second value in order to quickly adapt the actual combustion air ratio to the theoretical combustion air ratio.

[0032] The advantages of such a design of the power unit or such a method have been pointed out. Both the power unit and the method for operating the power unit can be improved according to the embodiments within the scope of the description, and thus reference is made to these embodiments.

[0033] The features and combinations of features described in the description, in particular those described in the following description of the drawings and / or shown in the figures, can be used not only in the given combination, but also in other combinations or individually, as long as the scope of the present invention is not departed from. Thus, embodiments that are not explicitly shown or explained in the description and / or the drawings but can be derived from or deduced from the explained embodiments are also considered to be included in the present invention. Description of the Drawings

[0034] The present invention will be described in more detail below with reference to the embodiments shown in the drawings, but the present invention is not limited thereto. Among them, the only

[0035] Figure 1Shows a plurality of diagrams in which the variation over time of different parameters related to an operating method for a power unit of a motor vehicle is plotted. Detailed implementation

[0036] According to Figure 1 A method for operating a power unit for a motor vehicle is described. The power unit has a power unit, during the operation of the power unit, a fuel-air mixture is at least temporarily supplied to the power unit, and the fuel-air mixture undergoes a chemical reaction, specifically combustion, in the combustion chamber of the power unit while forming exhaust gas. By introducing fuel into the combustion chamber, a fuel-fresh gas mixture is formed, wherein the introduction is carried out according to injection parameters. As injection parameters, for example, the number of injection pulses of the combustion chamber per working cycle of the power unit is used. In this regard, this number describes the frequency of introducing fuel into the combustion chamber in a time-discrete manner per working cycle (for example, by means of an injection valve / injector).

[0037] The composition of the fuel-fresh gas mixture used in the power unit is adjusted by means of air-fuel ratio regulation. For this purpose, the residual oxygen content in the exhaust gas downstream of the power unit, preferably upstream of the exhaust gas aftertreatment device of the power unit, is measured by means of an oxygen sensor. For example, the exhaust gas aftertreatment device is present as a vehicle catalytic converter. By means of air-fuel ratio regulation, the actual combustion air ratio is adjusted or regulated to the theoretical combustion air ratio, that is, by adjusting the composition of the fuel-fresh gas mixture.

[0038] Preferably, the air-fuel ratio regulation includes a plurality of control elements, such as a proportional control element (P element), an integral control element (I element), and a derivative control element (D element). In this regard, a PID controller is used for the air-fuel ratio regulation. The amplification factors of the control elements are selected such that during the normal operation of the power unit, the regulation of the actual combustion air ratio is continuously and stably carried out. This may result in that significant control deviations, that is, the difference between the theoretical combustion air ratio and the actual combustion air ratio, can only be corrected over a relatively long period of time. For example, such significant control deviations are caused by changes in the injection parameters. For this reason, it is stipulated that starting from the change in the injection parameters, the amplification factor is increased from a first value to a second value. Thus, a rapid reduction of the control deviation can be achieved.

[0039] Figure 1Four diagrams are shown, where in the bottom diagram, curve 1 of injection parameter 1 is shown. In the second diagram from the bottom up, curves 2 and 3 of the amplification factor are shown, that is, curve 2 represents the traditional operation method, and curve 3 represents the operation method described herein. In the third diagram from the bottom up, curves 4, 5, 6, 7, 8, and 9 show the operating modes of air-fuel ratio regulation. In the top, specifically the fourth diagram from the bottom up, curves 10 and 11 show the control deviation, that is, curve 10 represents the traditional operation method, and curve 11 represents the operation method described herein.

[0040] It can be seen that at time t 0 , the injection parameter changes. For example, the number of injection pulses per working cycle decreases, for example, from three to two. In the traditional operation method, according to curve 2, the amplification factor remains unchanged. In contrast, curve 3 shows that from time t 0 until time t 1 , the amplification factor is increased, that is, from the first value to the second value. Curves 4, 6, and 8 show the P element share (curve 4), the I element share (curve 6), and the total share of the control element (curve 8) of the traditional operation method. In contrast, curves 5, 7, and 9 show the P element share (curve 5), the I element share (curve 7), and the total share of air-fuel ratio regulation (curve 9) of the operation method described herein.

[0041] It can be clearly seen that due to the larger amplification factor of the I element, its share increases significantly, and thus a larger total is also obtained. This overall results in the control deviation shown by curves 10 and 11. It can be seen that compared with the traditional operation method according to curve 10, the traditional operation method according to curve 10 requires a significantly longer time to compensate for the changes caused by the change of the injection parameter. Generally speaking, a significantly faster correction of the control deviation can be achieved through the new operation method.

[0042] List of reference numerals

[0043] Curve 1

[0044] Curve 2

[0045] Curve 3

[0046] Curve 4

[0047] Curve 5

[0048] Curve 6

[0049] Curve 7

[0050] Curve 8

[0051] Curve 9

[0052] Curve 10

[0053] 11 Curve

Claims

1. A method for operating a power unit for a motor vehicle, the power unit having a power unit that generates exhaust gas, wherein, fuel is introduced into the combustion chamber of the power unit at least temporarily according to at least one injection parameter to form a fuel fresh gas mixture, wherein the actual combustion air ratio is determined based on the residual oxygen content in the exhaust gas measured by means of an oxygen sensor, and the actual combustion air ratio is adjusted to the theoretical combustion air ratio by adjusting the composition of the fuel fresh gas mixture by means of air-fuel ratio adjustment, characterized in that starting from the change of the at least one injection parameter, the amplification factor of at least one control element of the air-fuel ratio adjustment is increased from a first value to a second value in order to quickly adapt the actual combustion air ratio to the theoretical combustion air ratio.

2. The method according to claim 1, characterized in that, one of the following parameters is used as the at least one injection parameter: the number of injection pulses per working cycle, the injection position, the injection speed, and the injection duration.

3. The method according to any one of the above claims, characterized in that, the amplification factor is increased only when the fuel fraction in the composition of the fuel fresh gas mixture changes by at least 10%, at least 20%, or at least 30% due to the change of the at least one injection parameter.

4. The method according to any one of the above claims, characterized in that, the second value is selected to be at least 5 times, at least 7.5 times, or at least 10 times the first value.

5. The method according to any one of the above claims, characterized in that, an integral control element is used as the at least one control element.

6. The method according to any one of the above claims, characterized in that, the amplification factors of other control elements of the air-fuel ratio adjustment are kept constant.

7. The method according to any one of the above claims, characterized in that, after a specific time period, the increase in the amplification factor is cancelled.

8. The method according to any one of the above claims, characterized in that, the length of the time period is determined based on at least one of the following parameters: the exhaust gas delivery time from the power unit to the oxygen sensor, the load of the power unit, the rotational speed of the power unit, the torque provided by the power unit, and the temperature.

9. The method according to any one of the above claims, characterized in that, the length of the time period is selected such that the increase in the amplification factor terminates immediately after the change in the residual oxygen content in the direction determined by the change caused by the change of the at least one injection parameter ends.

10. A power unit for a motor vehicle, in particular a power unit for performing the method according to one or more of the above claims, wherein, The power plant has a power unit that generates exhaust gas, and at least temporarily inputs fuel into the combustion chamber of the power unit according to at least one injection parameter to form a fuel fresh gas mixture. Wherein, the actual combustion air ratio is determined according to the residual oxygen content in the exhaust gas measured by means of an oxygen sensor, and the composition of the fuel fresh gas mixture is adjusted by means of air-fuel ratio regulation to adjust the actual combustion air ratio to the theoretical combustion air ratio. It is characterized in that the power plant is arranged and designed such that starting from the change of the at least one injection parameter, the amplification factor of at least one control element of the air-fuel ratio regulation is increased from a first value to a second value in order to quickly adapt the actual combustion air ratio to the theoretical combustion air ratio.

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