Method for operating a device having an internal combustion engine and an electric motor

Abstract

The invention relates to a method for operating a device having an internal combustion engine and an electric machine, wherein the internal combustion engine has a crankshaft and the electric machine is torque-transmittingly coupled to the crankshaft, the electric machine being electrically connected to an energy storage device, wherein within a predefined operating range of the internal combustion engine, a current value (n max ) of the rotational speed (n) of the crankshaft is determined at a predefined crankshaft angle (1) within one working cycle (A) of the cylinders of the internal combustion engine.

Description

Field of the Invention

[0001] The present invention relates to a method for operating a device having an internal combustion engine and an electric motor, wherein the internal combustion engine has a crankshaft and the electric motor is torque-transmittingly coupled to the crankshaft, and the electric motor is electrically connected to an energy storage device. The present invention also relates to a computing unit and a computer program for implementing the method. Background Art

[0002] For an internal combustion engine, the rotational speed is increased by the kinetic energy generated during the working stroke, and then decreased by the subsequent exhaust stroke, intake stroke, and compression stroke. Thereby, certain rotational speed fluctuations are also generated within the working cycle of the cylinders of the internal combustion engine.

[0003] The higher the number of cylinders of the internal combustion engine, the more the rotational speed fluctuations can be at least partially compensated, wherein the working strokes of the cylinders of the internal combustion engine are also staggered from each other.

[0004] Therefore, especially for internal combustion engines with a small number of cylinders, such as those typically used in motorcycles, these rotational speed fluctuations can only be compensated for poorly. Summary of the Invention

[0005] According to the present invention, there is provided a method for operating a device having an internal combustion engine and an electric motor, having the features of the independent claims, and a computing unit and a computer program for implementing the method. Advantageous designs are the subject matter of the dependent claims and the following description.

[0006] The method according to the invention is for operating a device having an internal combustion engine and an electric motor, wherein the internal combustion engine has a crankshaft, the electric motor is torque-transmittingly coupled to the crankshaft, and the electric motor is electrically connected to an energy storage device, such as a battery. Herein, the internal combustion engine is especially considered to be an internal combustion engine having at most two cylinders, preferably exactly one cylinder, such as typically used in motorcycles.

[0007] Even if the proposed method is hereinafter described especially with reference to an internal combustion engine having (exactly) one cylinder, this can also be applied to internal combustion engines having two or more cylinders and can be used there.

[0008] As a supplement to the rotational speed fluctuations mentioned at the beginning in internal combustion engines, it has been shown that the kinetic energy generated in the cylinder during the working stroke - and thus also the resulting rotational speed changes - fluctuate statistically. This should be attributed, for example, to the different amounts of air supplied and the corresponding quality of combustion. This correspondingly also has an impact on the subsequent strokes and also on the subsequent working strokes. However, especially for such internal combustion engines with a small number of cylinders, this - and the generally common rotational speed fluctuations - can only be compensated for poorly, so that high rotational speed fluctuations occur overall there.

[0009] It is now possible to adjust to an as constant as possible rotational speed by adjusting the amount of air supplied to the cylinder and / or by adjusting the ignition timing of the internal combustion engine. This particularly relates to idling operation. However, in this case, each cylinder and each working cycle can only intervene once in a rotational speed adjustment manner, which cannot achieve particularly fast or good rotational speed adjustment especially for internal combustion engines with a small number of cylinders.

[0010] It is now proposed to determine the current value of the rotational speed of the crankshaft at a predetermined crankshaft angle within a working cycle of a cylinder of the internal combustion engine within a predetermined operating range of the internal combustion engine. Furthermore, the electric machine is controlled in such a way that the rotational speed is increased by torque transmission between the electric machine and the crankshaft when the current value is less than a corresponding comparison value (i.e., also at a predetermined crankshaft angle within the predetermined operating range of the internal combustion engine) and / or the rotational speed is decreased when the current value is greater than the comparison value.

[0011] Preferably, the crankshaft angle corresponding to the maximum rotational speed within the working cycle is used as the predetermined crankshaft angle within the working cycle. Such a maximum rotational speed typically occurs at the end of the working stroke.

[0012] It is also possible in particular to determine the energy difference between the energy currently provided by the internal combustion engine (i.e., especially the energy generated during the working stroke, which is converted into kinetic energy) and a comparison energy value by means of the current value and the comparison value of the rotational speed, and the electric machine is controlled in such a way that this energy difference is compensated for by torque transmission between the electric machine and the crankshaft.

[0013] The determination of such energy can be carried out, for example, with the aid of a model of the internal combustion engine taking into account the rotational speed. For a detailed elaboration on this, reference is made to the following explanations.

[0014] As a comparison value for the rotational speed, in the context of this method, in particular, the average value of the rotational speed within a plurality of working cycles (at a predefined crankshaft angle in a predefined operating range of the internal combustion engine) is considered. The average value is calculated arithmetically or otherwise, and the median can also be considered. It is also possible to use a model instead of taking the average value in order to obtain such a comparison value as an average value or a common value. The corresponding situation then also applies to the energy comparison value.

[0015] As can be seen from the above explanation, the current rotational speed at a predefined crankshaft angle is typically below or above the comparison value. By means of a suitable control of the electric machine, it is now possible to apply an accelerating torque or a braking torque to the crankshaft. In particular, it is possible to determine, with the aid of the energy difference mentioned, how precisely or strongly the electric machine must be controlled in an accelerating or braking manner for this purpose.

[0016] For example, the electric machine can be controlled in such a way that, starting from the current moment at which the parameter difference is calculated, the electric machine applies a torque to the crankshaft in a uniform or other distribution up to the crankshaft angle corresponding to the gas exchange top dead center. However, this can also be carried out beyond the gas exchange top dead center depending on the required energy output or energy absorption.

[0017] By means of the proposed method, it is now possible to compensate for rotational speed fluctuations caused by a statically inhomogeneous combustion process particularly effectively and, above all, particularly quickly. Compared to an intervention for regulating the rotational speed by means of an adjustment of the air quantity or the ignition timing, the electric machine can be controlled significantly faster.

[0018] The electric machine can generally be operated in motor mode or in generator mode, that is to say, electrical energy can be obtained from an energy storage device and output as mechanical energy as an accelerating torque to the crankshaft, or mechanical energy can be obtained from the crankshaft as a braking torque and fed as electrical energy to the energy storage device. Here, overall, it is possible to vary between the full motor power and the full generator power.

[0019] However, it is now also to be considered that the electric machine is typically used to generate electrical energy which is to be fed to an energy storage device and / or an on-board electrical network electrically connected thereto. The control of the electric machine as described above, that is to say, the accelerating or braking action on the crankshaft, can now be superimposed on the normal operation of providing electrical energy.

[0020] Here, the electric machine does not necessarily need to be operated in motor mode. More precisely, the accelerating action on the crankshaft can already be achieved by generating less energy for the energy storage device or the on-board electrical network. Viewed relatively - with respect to the braking action generated by the electric machine in normal operation - an accelerating action can nevertheless still be achieved.

[0021] In this regard, it is particularly preferred that, in addition, the electric machine is controlled in such a way that the voltage of the energy accumulator and / or the vehicle electrical system electrically connected thereto is maintained within a predefined nominal range. As an alternative or supplement to the voltage, the state of charge of the energy accumulator can also be used. Herein, in particular, the actual value of the voltage or the state of charge can be maintained within the nominal range or can also be changed. Hitherto, it has been common to regulate the voltage in the vehicle electrical system to a specific nominal value, while the use of a nominal range enables a certain variation of the voltage. By the aforementioned control of the electric machine - with an accelerating or braking action on the crankshaft during control - that is to say, there is also a following variation of the supplied voltage.

[0022] Herein, in particular, within the range of particularly rapid adjustment paths, the rotational speed is adjusted as an adjustment value to a predefined value by means of the nominal value of the voltage of the energy accumulator and / or the vehicle electrical system electrically connected thereto or the nominal value of the state of charge of the energy accumulator. In addition, it is preferred herein that, if the nominal value of the voltage of the energy accumulator and / or the vehicle electrical system electrically connected thereto or the nominal value of the state of charge of the energy accumulator reaches or exceeds the edge of the nominal range, the nominal value of the voltage or the state of charge is adjusted to a predefined value within the nominal range, in particular to a value centrally located within the nominal range, in the case of a change in the torque generated by the internal combustion engine. Thereby, the nominal torque of the internal combustion engine follows the continuously maintained (average) rotational speed deviation and the varying energy demand of the electrical system in a slower adjustment path.

[0023] In summary, a multi-parameter regulator is thereby provided which has, as input parameters, the power of the electric machine and the torque generated or provided by the internal combustion engine and, as output parameters, the voltage or the state of charge of the energy accumulator or the voltage of the vehicle electrical system electrically connected thereto and in particular the rotational speed as the idling speed. It is taken into account here that, on the one hand, the voltage or the charge is adjusted by changing the power of the electric machine, but there is also a cross-coupling to the rotational speed, since the rotational speed decreases (which in turn affects the power of the electric machine) due to an increase in the power of the electric machine (especially in generator mode of operation). The torque of the internal combustion engine mainly affects the rotational speed, wherein, therewith, the power of the electric machine is also changed as the rotational speed changes and this then has an impact on the voltage or the state of charge.

[0024] By means of the two aforementioned adjustment paths, it is now possible, on the one hand, to adjust the rotational speed as well and as specifically as possible, but if necessary, the voltage or the state of charge can also be corrected in such a way that it is maintained within a predefined nominal range. In summary, this also has a positive impact on possible harmful substance emissions.

[0025] Advantageously, the power of the electric machine can only be changed once per working cycle and / or not during the injection process and / or not during the charging of the ignition coil of the internal combustion engine. This enables the achievement that the combustion or the combustion process itself is affected as little as possible.

[0026] During the idling operation of the internal combustion engine, there occur in particular so-called dragging (unexpectedly poor) combustion and associated rotational speed disturbances. In contrast, for too good combustion, there occur only few and minor associated rotational speed increases.

[0027] Since the maximum possible efficiency of the on-board electrical system can be achieved when the power output of the electric machine is kept as constant as possible, for the sake of this efficiency, torque regulation interventions on the electric machine can be dispensed with when the combustion is too good. Instead, in these cases, a slight rotational speed overshoot is tolerated and torque interventions are carried out with the electric machine only when the combustion is dragging, for the sake of rotational speed stability. In other words, the electric machine is preferably controlled in such a way that the rotational speed is increased when the current value is less than a corresponding comparison value and the rotational speed is not decreased when the current value is greater than the comparison value, by means of torque transmission between the electric machine and the crankshaft.

[0028] It is particularly preferred to use the idling operation as a predefined operating range of the internal combustion engine. Since particularly large rotational speed fluctuations occur during idling operation, better idling can be achieved with the proposed method. In particular, in this way, the idling speed can even be reduced. However, the proposed method is also applicable to other operating ranges, especially operating ranges with low load and / or low rotational speed (but above the idling speed).

[0029] Overall, therefore, the adjustment of the ignition angle for rotational speed regulation can be dispensed with and the ignition angle can thus be constantly adjusted to an optimal value. This directly results in a more efficient or more intense combustion. Accordingly, the amount of air and fuel per combustion can be reduced and thus the consumption and emissions of the combustion engine can be reduced.

[0030] In particular, it is also possible, for example, on a computing unit, if necessary, to model an energy accumulator, especially configured as a battery, and also its state by means of an additional measurement of the battery current and thus to obtain the charge state of the energy accumulator. In this case, the above-described regulation scheme can, as already mentioned, regulate the charge state instead of the voltage or can be extended in such a way that the voltage (charging voltage) is adjusted within a rated range and at the same time the desired charge state is regulated.

[0031] The computing unit according to the invention, for example the controller of a motor vehicle, is in particular technically configured in terms of programming to carry out the method according to the invention.

[0032] It is also advantageous to implement the method according to the invention in the form of a computer program or computer program product with a program code for implementing all method steps, since this results in particularly low costs, in particular if the executing controller is also used for other tasks and is therefore already present. Suitable data carriers for providing the computer program are in particular magnetic, optical and electrical memories, such as hard disks, flash drives, EEPROMs, DVDs, etc. The program can also be downloaded via a computer network (Internet, intranet, etc.).

[0033] Further advantages and embodiments of the invention are apparent from the description and the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] The invention is schematically illustrated in the drawings on the basis of exemplary embodiments and is described below with reference to the drawings.

[0035] Figure 1 A device having an internal combustion engine and an electric machine is schematically shown, with which the method according to the invention can be carried out.

[0036] Figure 2 The speed curve of an internal combustion engine is schematically shown in order to explain a preferred specific embodiment of the method according to the invention.

[0037] Figure 3 The sequence of another preferred specific embodiment of the method according to the invention is schematically shown.

[0038] Figure 4 The sequence of another preferred specific embodiment of the method according to the invention is schematically shown. DETAILED DESCRIPTION

[0039] exist Figure 1 Schematically shows a device 100 with an internal combustion engine 110 and an electric machine 120 , with which the method according to the invention can be carried out. The internal combustion engine 110 is designed as an internal combustion engine with a cylinder 111 and a crankshaft 115 , for example.

[0040] Electric machine 120 is coupled to crankshaft 115 and thus also to internal combustion engine 110 in a torque-transmitting manner. Electric machine 120 is also electrically connected to energy storage device 130, which can be a battery, for example, that is, electrical energy can flow from electric machine 120 to energy storage device 130 and vice versa. In addition, the vehicle electrical system can be electrically connected to energy storage device 130.

[0041] By means of a computer unit 140 designed as a controller, the electric machine 120 can be controlled accordingly, that is, a torque-absorbing or generator operation can be carried out, in which electrical energy flows from the electric machine 120 to the energy storage device 130. Likewise, a torque-generating or motor operation can be carried out, in which electrical energy flows from the energy storage device 130 to the electric machine 120, if necessary.

[0042] Furthermore, an angle sensor 116 is provided on or for crankshaft 115 , by means of which the current crankshaft angle and, if necessary, also the rotational speed can be detected and supplied to control unit 140 .

[0043] exist Figure 2 The internal combustion engine, in particular Figure 1 . For this purpose, the speed n is plotted over time t. The speed trend shown here corresponds to the speed trend in idling operation. Since the internal combustion engine has only one cylinder, relatively large speed fluctuations occur.

[0044] Here, a total of three working cycles A can be seen, each of which has a working stroke, an exhaust stroke, an intake stroke and a compression stroke. The ignition top dead center ZOT and the gas exchange top dead center GOT are drawn in as an example. Therefore, within a working cycle, the minimum speed occurs approximately at ZOT, and the maximum speed occurs after a crankshaft angle of approximately 90° to 180°. At GOT, the speed is at an intermediate value.

[0045] In addition to the speed fluctuations within the working cycle, it can also be seen that the maximum (and also the minimum) speed within the working cycle varies from working cycle to working cycle. The different values ​​for the maximum speed are denoted by n max,soll and n max As explained at the outset, this should be attributed, for example, to statistical deviations of the combustion process.

[0046] By way of example and in order to explain the proposed method, the maximum speed is expressed as n max,soll The numerical values ​​indicated below should correspond to intermediate values ​​and therefore serve as comparison values.

[0047] The purpose of the regulation or control within the scope of the proposed method is, for example, to set the speed at the start of the intake opening to the same value in each working cycle. In this case, the intake opening point is shortly before the GOT. The starting point is then, for example, at a predetermined crankshaft angle 1, approximately 180°KW after ZOT, the maximum speed, that is, for example, the value n max .

[0048] Calculated by comparison with a comparison value or the maximum expected rotational speed n max,soll to calculate how much more or less energy is generated by combustion compared to a median or typical combustion. If too much energy is generated, the excess energy is stored in an accumulator by means of an electric motor, for example, until the time of the GOT. If too little energy is generated, this energy is fed into the system by means of the electric motor.

[0049] Particularly good combustion typically only feeds slightly more energy into the system than the average case. In contrast, poor or delayed combustion feeds significantly less energy into the system than the average case. Therefore, within the scope of the proposed method, the overall accelerating effect on the crankshaft is greater than the braking effect.

[0050] The calculation of the energy difference ΔE can be carried out, for example, in a squared manner and is then calculated as:

[0051] .

[0052] Here, the constant C T is related to the moment of inertia of the internal combustion engine at the crankshaft angle 1 and can be learned in the system or applied appropriately, for example.

[0053] To obtain the current comparison value n max,soll,i , for example, the effective average of all the measured values so far can be calculated. Then, by means of a recursive filter as

[0054] the comparison value is obtained.

[0055] Similarly, as long as the averaging is carried out to a sufficient depth, other calculations for averaging are also possible. Possible filter coefficients for the above-mentioned equation are, for example, M = 50 to M = 100. However, depending on the target system, smaller / larger values may also be preferably used. In this case, the first measured rotational speed is equated to the first average rotational speed.

[0056] The regulation desire for the electric motor can be derived from the calculated energy difference ΔE. The missing or excess energy is compensated for electrically within the same working cycle until another (constant) crankshaft angle 2. In this case, a suitable position can be, for example, the 360° crankshaft angle after 1.

[0057] The position is advantageously selected such that a constant battery voltage is achieved during the injection and ignition durations, that is, the electric motor maintains its output power as constant as possible and 2 does not fall within these two ranges.

[0058] To compensate for the energy difference, it is necessary to apply or remove the corresponding electrical energy during the crankshaft angle interval from 1 to 2. For this purpose, the necessary time interval Δt for the crankshaft angle interval is calculated using the following equation, namely:

[0059] ,

[0060] where the average rotational speed, especially the idling speed, is represented by n soll . The factor "6°" in the denominator results from the use of the rotational speed in rpm or revolutions per minute (U / min). In other words, for the frequency (1 / s), the factor "360°" must be used. Here, the angles are in degrees respectively, not in radians. The inaccuracies that occur here can be ignored by using the rated rotational speed instead of the actual average rotational speed, which is still unknown at the moment at 1, during the interval. The required power P of the electric motor for this time can be calculated from the calculated time interval:

[0061] .

[0062] To supply electrical energy to the vehicle electrical system or the energy storage device, the corresponding power of the electric motor must be continuously set in generator mode. Therefore, the electrical power calculated above should be added as an offset to the basic power.

[0063] Since the internal combustion engine is typically regulated in such a way by the motor controller that the desired rotational speed n soll is on average adhered to, the average output power of the electric motor only varies due to the efficiency of the energy conversion in the energy storage device, the electric motor, and the control hardware.

[0064] If instead of using the torque calculation or power calculation of the electric motor, the regulation of the rotor angle is used, the rotor angle difference Δδ can also be directly calculated from the energy difference with the aid of a conversion factor while ignoring the inaccuracies that occur here. Therefore, it holds that:

[0065] .

[0066] These two constants can be summarized as a combined constant C:

[0067] .

[0068] The calculated rotor angle offset Δδ is added to the instantaneously regulated rotor angle and on average, as in the case of power above, it results in zero because the internal combustion engine can alone adhere to the rated rotational speed on average.

[0069] exist Figure 3 The sequence of a preferred specific embodiment of the method according to the invention is schematically shown in . As already mentioned above, a multi-parameter controller can be used within the scope of the proposed method.

[0070] This is shown by way of example using the input variables of power P of the electric machine and torque M generated or provided by the internal combustion engine and using the output variable of voltage U of the energy storage device or of an onboard electrical system electrically connected thereto and in particular speed n as idling speed.

[0071] Here, it is also expressed that, on the one hand, the voltage U is regulated by changing the power P, but at the same time there is a cross-coupling to the speed n, since the speed decreases (which in turn influences the power of the electric machine) due to the increase in the power output of the electric machine (especially in generator operation). The speed n is primarily influenced by the torque M, wherein the power P in turn changes with the change in the speed n and this then has an influence on the voltage U.

[0072] exist Figure 4 The flow of a preferred embodiment of the method according to the invention is schematically shown in . Usually, the voltage U is adjusted by the power P of the electric machine. For example, the voltage U can be adjusted by adjusting the rotor angle.

[0073] However, within the scope of the proposed method, it is now provided that, instead of regulating to a constant voltage or a setpoint value of the voltage, the voltage is kept within a suitable setpoint range. In particular, in the idling operating range, a new setpoint value for the voltage of the internal combustion engine and a new value for the torque of the internal combustion engine are calculated by comparing the setpoint speed with the actual speed with the aid of a suitable controller or algorithm.

[0074] For this purpose, in particular within the scope of the fast control path, in order to stabilize the speed n, that is to say to adjust to the set speed n soll , and the rated value of the voltage U soll When the speed is too high, the rated value U for the voltage is increased. soll To achieve this, the power output of the electric machine is then increased and the speed is reduced. If the speed is too low, the rated value U of the voltage is reduced and the power output of the electric machine is thus reduced or even the power is delivered as a motor and the speed is thus increased.

[0075] Here, the voltage can be adjusted to the corresponding rated value with the power of the motor as a regulating value in the sense of a lower-level regulator. However, in this case, unregulated control can also be considered. Regarding the specific method for regulating the power of the motor, reference should be made to the previous explanations.

[0076] Here, the rated value U of the voltage soll is only allowed to vary, in particular, within the rated range:

[0077] .

[0078] The minimum value U soll,min can be, for example, 12.5 V and the maximum value U soll,max can be, for example, 14.3 V. Before or when exceeding these limits, or when reaching or exceeding the edge of the rated range U B , the torque M of the internal combustion engine can be changed in a slow path and thereby the rated value U of the voltage can be adjusted soll such that the new rated value is centered within the rated range U B . As already mentioned, the rotational speed can be increased by increasing the torque, which increases the power of the motor and thereby the voltage. The corresponding situation applies to the reduction of power and voltage.

[0079] By the proposed method, the internal combustion engine can be kept largely at a constant operating point to a great extent by using the motor when adjusting the rotational speed, especially the idle speed, which has a positive impact on emissions and consumption.

Claims

1. A method for operating a device (100) having an internal combustion engine (110) and an electric motor (120), wherein the internal combustion engine has a crankshaft (115) and the electric motor is torque-transmittingly coupled to the crankshaft, and the electric motor is electrically connected to an energy storage device (130), wherein within a predetermined operating range of the internal combustion engine (110) within one working cycle (A) of a cylinder (111) of the internal combustion engine, a current value (n ) of the rotational speed (n) of the crankshaft is determined at a predetermined crankshaft angle max , and The electric machine (120) is controlled such that the rotational speed (n) is increased by torque transmission between the electric machine (120) and the crankshaft when the current value (n max ) is less than a corresponding comparison value (n max,soll ), and / or the rotational speed is decreased when the current value (n max ) is greater than the comparison value (n max,soll ). The crankshaft angle corresponding to the maximum rotational speed within the working cycle is used as the pre-determined crankshaft angle (φ1) within the working cycle. In addition, the electric machine (120) is controlled in such a way that the voltage (U) of the energy accumulator (130) and / or the voltage of the vehicle electrical system electrically connected thereto and / or the state of charge of the energy accumulator is maintained within a predefined nominal range (U B ), wherein the rotational speed (n) is adjusted as a regulated variable to a predefined value (n soll ) by means of the nominal value (U soll ) of the voltage of the energy accumulator and / or of the vehicle electrical system connected thereto or the state of charge of the energy accumulator, Among them, If the rated value (U soll ) of the voltage of the accumulator and / or the on-board electrical system or the state of charge of the accumulator reaches or exceeds the edge of the rated range (U B ), then, in the case of a change in the torque (M) generated by the internal combustion engine (110), the rated value (U soll ) of the voltage or the state of charge is adjusted to a predefined value within the rated range (U B ).

2. The method according to claim 1, wherein an energy difference between the energy currently provided by the internal combustion engine and a comparative energy value is determined based on the current value (n max ) of the rotational speed and a comparative value (n max,soll ), and wherein the electric machine (120) is controlled such that the energy difference is compensated for by torque transmission between the electric machine (120) and the crankshaft (115).

3. The method according to claim 1 or 2, wherein the electric machine (120) is controlled such that the rotational speed (n) is increased by torque transmission between the electric machine (120) and the crankshaft when the current value (n max ) is less than a corresponding comparison value (n max,soll ), but the rotational speed is not reduced when the current value (n max ) is greater than the comparison value (n max,soll ).

4. The method according to claim 1, wherein If the rated value (U soll ) of the voltage of the accumulator and / or the on-board electrical system or the state of charge of the accumulator reaches or exceeds the edge of the rated range (U B ), then, in the case of a change in the torque (M) generated by the internal combustion engine (110), the rated value (U soll ) of the voltage or the state of charge is adjusted to a value that is centered within the rated range.

5. The method according to claim 1 or 2, wherein the power (P) of the electric machine (120) is changed only once per working cycle and / or is not changed during the injection process and / or is not changed during the charging of the ignition coil of the internal combustion engine (110).

6. The method according to claim 1 or 2, wherein idling operation is used as the pre-defined operating range of the internal combustion engine (110).

7. The method according to claim 1 or 2, wherein an internal combustion engine with at most two cylinders is used as the internal combustion engine.

8. The method according to claim 1 or 2, wherein an internal combustion engine with exactly one cylinder is used as the internal combustion engine.

9. A computing unit (140) configured to perform all method steps of the method according to any one of the preceding claims 1 - 8.

10. A computer program product which, when executed on a computing unit (140), causes the computing unit (140) to perform all method steps of the method according to any one of claims 1 to 8.

11. A machine-readable storage medium having stored thereon a computer program which, when executed on a computing unit (140), causes the computing unit (140) to perform all method steps of the method according to any one of claims 1 to 8.

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