Computer-implemented method for converting and / or using an internal combustion engine for operation with a climate-neutral fuel

Abstract

A computer-implemented method (100) is provided for converting and / or using an internal combustion engine designed for operation with a fossil fuel for operation with a climate-neutral fuel. The method (100) comprises detecting (S1) fossil combustion variables during operation of the internal combustion engine with the fossil fuel, wherein the fossil combustion variables include a fossil combustion duration, a fossil combustion profile, and a first air-fuel-water ratio, and determining (S2) a climate-neutral combustion duration and a climate-neutral combustion profile during operation of the internal combustion engine with the climate-neutral fuel and the first air-fuel-water ratio based on the fossil combustion variables.The method (100) comprises adapting (S3) the climate-neutral combustion duration to the fossil combustion duration and the climate-neutral combustion profile to the fossil combustion profile, wherein the first air-fuel-water ratio is changed to a second air-fuel-water ratio, and outputting (S4) at least one parameter and / or at least one control signal for controlling the internal combustion engine for operation with the climate-neutral fuel as a function of the adapted climate-neutral combustion duration and the adapted climate-neutral combustion profile.

Description

[0001] The present disclosure relates to a computer-implemented method for converting and / or using an internal combustion engine designed for operation with a fossil fuel for operation with a climate-neutral fuel, as well as to a data processing device designed to at least partially carry out the method. Additionally or alternatively, a computer program is provided which comprises instructions which, when executed by a computer, cause the computer to at least partially carry out the method. Additionally or alternatively, a computer-readable medium is provided which comprises instructions which, when executed by a computer, cause the computer to at least partially carry out the method.

[0002] For the development of modern internal combustion engines (e.g. for motor vehicles), knowledge of the combustion behavior of a specific air-fuel mixture is necessary in order to be able to apply modern engine development processes (pre-calculation and simulation). This knowledge is also necessary in later development processes, whereby, among other things, an engine control unit (electronic control unit, ECU) is required for a corresponding motor vehicle in series production. This unit must be able to calculate the influence of the specific composition of the air-fuel mixture on combustion at any time and regulate the engine accordingly. This is important to ensure safety for humans and machine, but also for the precise adjustment of, among other things, load, speed, efficiency and fuel consumption, which has a corresponding influence on emissions (e.g. nitrogen oxides and CO2).

[0003] The emergence of CO2-neutral fuels for use in combustion engines poses challenges to proven engine development processes and engine control systems due to the changed combustion behavior. The combustion of hydrogen (H2) and ammonia (NH3) differs greatly from that of hydrocarbons (C x H y ), such as gasoline and diesel. But also synthetic fuels (e-fuels), which are based on artificially produced hydrocarbon compounds (C x H y ) differ from crude oil-based fuels because there are no natural impurities (e.g. sulfur) and, furthermore, the final composition (location-dependent regulations, approvals, etc.) of the e-fuels and their optimization with regard to combustion behavior have not yet been clearly defined or completed.

[0004] Due to new fuels and their new combustion properties, frontloading is no longer possible to the extent that was previously the case with established fossil fuels. With the help of sophisticated simulation programs, frontloading shifted cost- and time-intensive engine experiments to a much earlier project phase, with the goal of distributing the workload as consistently as possible throughout the entire project phase.

[0005] Furthermore, for the new fuels, especially hydrogen, the continued use of current engine control units is only possible to a limited extent, as these were developed over decades for fossil, hydrocarbon-based fuels.

[0006] To utilize climate-neutral or CO2-neutral fuels, the most accurate modeling of the combustion process is necessary to develop new combustion engines for climate-neutral fuels and / or to convert (i.e., retrofit) existing combustion engines designed for fossil combustion engines. Currently, two different approaches to modeling the combustion process are known: a non-predictive approach and a predictive approach.

[0007] The non-predictive approach uses a combustion curve calculated from a so-called pressure curve analysis. In pressure curve analysis, the first law of thermodynamics is applied according to the closed system of the engine combustion chamber and adapted according to the energy release rate of the fuel, i.e., the combustion described by the combustion curve. The terms required to calculate the combustion curve, such as the cylinder pressure curve, the mass flows, and the fuel composition, are determined from measurement data from the engine test bench. This makes the obtained combustion curves non-predictive, since these combustion curves can only be used to calculate operating points in the simulation that correspond to the measured operating point, especially with regard to the center of combustion, the fuel composition, the air-fuel-water ratio, but also the load, the speed, and the turbulence level.

[0008] The non-predictive approach is nevertheless very common because the simulation calculates additional physical variables at the measured operating points that cannot be measured or can only be measured with great effort, e.g., the turbulence level after a charge cycle and / or a residual gas fraction. If different operating points are calculated using the combustion profiles (especially if the center of combustion, fuel composition, and / or the air-fuel-water ratio differ), the predictive quality of the results drops significantly. Accordingly, the application of these non-predictive combustion profiles in preliminary investigations for hydrogen, ammonia, and also hydrocarbon-based e-fuels will lead to very inaccurate results, as the reaction kinetic properties differ significantly from those of (fossil) hydrocarbons.Currently, dedicated measurement data from combustion engines, especially those using hydrogen, ammonia, and their combinations and / or admixtures with, for example, natural gas, are very rare. Therefore, the classic non-predictive approach is not applicable. In the predictive approach, the combustion process is directly calculated in the simulation based on a variety of formulas. This is done, among other things, using the so-called entrainment model, which uses a thermodynamic two-zone model to describe the absorption of the air-fuel mixture into the flame propagating in the combustion chamber. For the development of the entrainment model, NC Blizard and JC Keck (“Experimental and Theoretical Investigation of Turbulent Burning Model for Internal Combustion Engines”, SAE International, 1974, pp. 846-864) and for further development, RJ Tabaczynski (“A Turbulent Entrainment Model for Spark-Ignition Engine Combustion”, SAE International, 1977, pp. 2414-2433) and C.Chen ("A Refinement of Flame Propagation Combustion Model for Spark-Ignition Engines," SAE International, 1992, pp. 1346-1367) made a significant contribution. However, the formulas used in the predictive approach only describe qualitative or relative trends. Therefore, calibration with measurement points from test bench data (calibration points) is always necessary to use the calculation for quantitative or absolute results.

[0009] The predictive approach is less widespread because calibration with test bench data is still necessary, and therefore the additional effort of calibration is avoided by directly resorting to the non-predictive approach. Furthermore, the classic model of the laminar flame speed, developed by M. Metghalchi and J.C. Keck ("Burning velocities of mixtures of air with methanol, isooctane, and indolene at high pressure and temperature", 1982, pp. 191-210) and further developed by J.B. Heywood ("Internal Combustion Engine Fundamentals", 1st edition, McGraw-Hill Inc., 1988), is very inaccurate for values ​​for fuel composition and air-fuel-water ratio that deviate from the calibration point. This is demonstrated in detail by S. Hann ("Reaction Kinetics Calculations and Modeling of the Laminar Flame Speeds of Gasoline Fuels", SAE International, 2018) and developed based on an approach by J.Ewald ("A level set based flamelet model for the prediction of combustion in homogeneous charge and direct injection spark ignition engines", Cuvillier Verlag, 2006) developed a new model of the laminar flame speed for hydrocarbons at considerable expense. The same approach can be repeated for hydrogen based on the approach of S. Verhelst ("A Study of the Combustion in Hydrogen-Fueled Internal Combustion Engines", Ghent University, 2005).

[0010] DE 10 2021 209 209 A1 relates to a method for controlling an internal combustion engine by means of a calculated pressure curve in a cylinder of the internal combustion engine as well as a computing unit and a computer program for carrying out the method.

[0011] The fundamental disadvantage of the predictive approach is that the magnitude of the error in the prediction quality is not limited, resulting in distrust of the results. This means that the deviation from the predictively calculated operating point to the point measured on the test bench, which does not correspond to a calibration point, can be immensely high (e.g., twice or half the actual peak combustion pressure). This fact is particularly critical when the predictive approach is used for operating points for which no test bench data is available for validation. If the approach delivers a low prediction quality in such a case, it is impossible to determine the maximum deviation with which the result corresponds to reality, since there is no limit to the maximum error size.

[0012] The simulation result may therefore deviate by orders of magnitude and still appear to deliver plausible results, especially for fuels for which there are few or no references in combustion engines (e.g., hydrogen and ammonia).

[0013] To function, existing solutions for modeling the combustion process require measurement data from an engine that has already been converted to a climate-neutral or CO2-neutral fuel and a corresponding new air-fuel-water ratio. This means that cost-intensive hardware (i.e., an engine test bench) must be set up at a very early stage of development. So-called frontloading is therefore not possible. Without test bench data, neither the non-predictive nor the predictive approach can be applied.

[0014] Furthermore, the predictive approach with a variable air-fuel-water ratio inadequately reflects the influence on combustion. This is due to the laminar flame speed model, which can have a high error rate due to the engine range of pressure, temperature, and air-fuel-water ratio, within which wide extrapolation is required. Even with a remodeling following the model developed by S. Hann based on the approach of S. Verhelst, the wide extrapolation remains a factor that prevents the laminar flame speed model from being robustly applicable. As a result, aspects such as time, cost, and quality suffer. The barrier to entry into new climate-neutral fuels (e.g., hydrogen, ammonia, and their combinations or blends) is currently high, leading to delays in series production.

[0015] Against the background of this prior art, the object of the present disclosure is to provide a device and / or a method which are each suitable for enriching the prior art.

[0016] The problem is solved by the features of the independent claims. The subordinate claims and the dependent claims each contain optional developments of the disclosure.

[0017] The task is then solved by a computer-implemented method for converting and / or using an internal combustion engine designed for operation with a fossil fuel for operation with a climate-neutral fuel.

[0018] The method comprises detecting fossil combustion variables during operation of the internal combustion engine with the fossil fuel, wherein the fossil combustion variables include a fossil combustion duration, a fossil combustion profile and a first air-fuel-water ratio (optionally also: first air-fuel ratio and / or combustion ratio).

[0019] The method comprises determining a climate-neutral combustion duration and a climate-neutral combustion profile when operating the internal combustion engine with the climate-neutral fuel and the first air-fuel-water ratio based on the fossil combustion parameters.

[0020] The method comprises adapting the climate-neutral combustion duration to the fossil combustion duration and the climate-neutral combustion profile to the fossil combustion profile, wherein the first air-fuel-water ratio is changed (e.g. reduced) to a second air-fuel-water ratio (optionally also: second air-fuel ratio and / or combustion ratio).

[0021] The method comprises outputting at least one parameter and / or at least one control signal for controlling the internal combustion engine for operation with the climate-neutral fuel as a function of the adapted climate-neutral combustion duration and the adapted climate-neutral combustion profile.

[0022] The climate-neutral fuel is a CO2-neutral or CO2-free fuel that, for example, does not release any (additional) CO2 during combustion. The climate-neutral fuel can be hydrogen (H2), ammonia (NH3) and / or an e-fuel (e.g., a synthetic hydrocarbon (C x H y )). The fossil fuel may be a fuel derived from natural gas and / or petroleum, e.g., gasoline and / or diesel.

[0023] The (first and / or second) air-fuel-water ratio can be or include a combustion air ratio (also known as an air ratio). The combustion air ratio can specify the mass ratio of air to (e.g., fossil or climate-neutral) fuel (e.g., relative to the respective stoichiometrically ideal ratio for a theoretically complete combustion process).

[0024] The (first and / or second) air-fuel-water ratio may include a water content (and thus, for example, the combustion air ratio and the water content). The (first and / or second) air-fuel-water ratio may, for example, specify the mass ratio of air to (e.g., fossil or climate-neutral) fuel to water (e.g., relative to the respective stoichiometrically ideal ratio for a theoretically complete combustion process).

[0025] The combustion duration can be understood as the time required for (e.g., complete) combustion of the (fossil or climate-neutral) fuel during an ignition or combustion process (and / or in an engine cycle) while the internal combustion engine is operating. The combustion duration can, for example, extend from the formation of a spark to the end of fuel combustion (in a combustion chamber of the internal combustion engine) or, for example, from the beginning of a pressure increase to the end of combustion. The combustion duration can be a period of time, specified, for example, in seconds. Alternatively, it is conceivable that the combustion duration is specified as a function of a crank angle (abbreviated to °CA) of a cylinder of the internal combustion engine.

[0026] The combustion curve refers to the release or generation of heat energy through the combustion of (fossil or climate-neutral) fuel during an ignition or combustion process (and / or in an engine cycle) in the operation of the internal combustion engine. The combustion curve can be specified as a function of the crank angle of a cylinder of the internal combustion engine.

[0027] "Conversion and / or use of an internal combustion engine" means that the method provides a modified control of the internal combustion engine designed for operation with the fossil fuel in order to be able to operate the internal combustion engine with the climate-neutral fuel instead of the fossil fuel. In order to take into account the new conditions for operation with the climate-neutral fuel, in particular the combustion behavior of the climate-neutral fuel that differs from that of the fossil fuel, the at least one parameter (e.g., a pressure curve of at least one cylinder of the internal combustion engine) and / or the at least one control signal is determined and output as a function of the adapted climate-neutral combustion duration and the adapted climate-neutral combustion curve.By means of the at least one parameter and / or the at least one control signal, the internal combustion engine can thus be controlled in such a way that, when operating with the climate-neutral fuel, the same or at least similar combustion characteristics (i.e., combustion duration and combustion process) occur as in the original operation with the fossil fuel, which leads to the same or at least similar loads and requirements for the internal combustion engine.

[0028] The method can be carried out both during (pre-)development and during operation of the internal combustion engine. During (pre-)development, the method can be used to provide a modified engine control system for the internal combustion engine. For example, the at least one parameter for the (already existing) internal combustion engine can be determined and output in order to then be retrievably loaded into an engine control unit of the internal combustion engine. The engine control unit is thus able to ensure operation with the climate-neutral fuel by controlling the internal combustion engine during operation by generating control signals depending on the at least one new parameter. Alternatively, or in addition to use in (pre-)development, the method can be carried out during operation of the internal combustion engine. For this purpose, the engine control unit of the internal combustion engine can be designed to carry out the method.For example, the at least one parameter and the at least one control signal (e.g. depending on the at least one parameter) can be determined and output by the engine control unit in order to control the internal combustion engine by the at least one control signal.

[0029] The method is a computer-implemented method, i.e. one, several or all steps of the method can be carried out at least partially by a computer or a data processing device, optionally an edge device.

[0030] The method described above offers a number of advantages. Among other things, it provides a technique for finding the climate-neutral fuel with the modified, e.g., diluted, second air-fuel-water ratio, which has the same combustion characteristics as the fossil (reference) fuel with the first air-fuel-water ratio. Identical combustion characteristics advantageously lead to the same load and similar requirements for the combustion engine after the conversion (also: retrofit). This new approach enables the most accurate modeling of a combustion process for combustion engines and thus offers the possibility of operating or further developing existing, already produced or developed combustion engines in a climate-neutral, e.g., CO2-free, manner with the fewest possible modifications. This includes, among other things, adapting the combustion characteristics, e.g.The combustion duration and combustion process are necessary to correctly represent the influences of variable air and water proportions with a constant fuel. This is particularly necessary, for example, in a hydrogen engine (i.e., a hydrogen-powered combustion engine), which, due to its properties, can and must be operated with a wide air-fuel ratio as well as an air-fuel-water ratio in order to always achieve the best possible efficiency, smoothness, and NO emissions. x -reduction.

[0031] The influence of the specific fuel composition, i.e. the composition of the mixture of the climate-neutral fuel with air and water (defined by the air-fuel-water ratio), on combustion can be determined or modeled as precisely as possible, e.g., in real time. The mixture can be made up of any fuel composition (e.g., C x H y, H2, NH3) and also any desired air-fuel or air-fuel-water ratios. The method uses the combustion data of an existing fossil combustion engine that is to be converted to a climate-neutral (e.g., CO2-free) fuel. The fossil combustion engine thus serves as the base engine and thus as a reference or starting point for the method described above. This approach advantageously leads to a high degree of robustness, precision, and real-time capability of the method.

[0032] Thus, by mapping the influence of the fuel (or fuel type) and the air-fuel-water ratio on the combustion duration, the combustion process and optionally other combustion parameters as accurately as possible, very rapid frontloading (or rapid concept assessment and / or pre-development) is advantageously enabled, as has so far only been possible for conventional fossil fuels.

[0033] The method according to the present disclosure offers, among other things, various advantages in different development and deployment phases. In an early development phase (e.g., when converting the combustion engine), the most precise results and statements regarding the correct engine design with the climate-neutral fuel can be achieved. This enables time and cost savings through so-called frontloading, whereby, for example, the increased degree of development at the start of the test phase can eliminate costly geometry variations. In the application phase, the application time can be shortened, since, for example, the number of parameters that must be applied manually is reduced by storing a physics-based function.

[0034] The influence of fuel composition on combustion, more specifically on the combustion process and duration, can advantageously be mapped as precisely as possible in calculations and simulations during the early (pre-)development phase. Frontloading is thus also possible for new, climate-neutral fuels. The speed of (pre-)development of climate-neutral, e.g., CO2-free, combustion engines can thus be significantly accelerated and brought to market readiness. This will lead to a corresponding reduction in CO2 emissions.

[0035] Furthermore, for frontloading or initial concept assessments, no new measurement data or test bench data are required for initial concept assessments in an early project phase using the procedure described above, since existing reference combustion parameters of the combustion engine designed for fossil fuel can be used.

[0036] The method described above can also be used for engine control on a test bench or in an engine control unit and thus in a series application, enabling, for example, a real-time reaction or control for the most optimal adjustment of combustion with regard to efficiency, load, power, emissions, etc.

[0037] The physical influence of fuel composition can also be empirically confirmed, resulting in a very robust method without calibration, meaning there is a limit to the maximum error deviation, e.g., compared to a predictive approach. This empirical-physical approach is also very robust due to its validation and application to existing reference combustion parameters. Furthermore, this empirical-physical approach can serve as a basis for additional models (knocking, pre-ignition) that have a strong influence on the estimation of power, efficiency, emissions, component lifetime, etc. This enables, among other things, the most precise simulation possible in (pre-)development.

[0038] Possible further developments of the procedure described above are explained in detail below.

[0039] The at least one parameter can comprise a pressure profile of at least one cylinder (or in at least one cylinder and / or in a combustion chamber) of the internal combustion engine. Outputting the at least one parameter and / or the at least one control signal can comprise calculating the pressure profile for the adjusted climate-neutral combustion duration and the adjusted climate-neutral combustion profile, and outputting the calculated pressure profile and / or at least one control signal as a function of the calculated pressure profile.

[0040] It should be noted that the combustion duration or combustion profile (i.e. the rate at which the chemical energy of the fuel is converted during combustion) determines how a cylinder pressure profile increases. The pressure in the cylinder's combustion chamber exerts a force on the crankshaft drive, which is transmitted to the drive wheels of the vehicle at the end of the chain and drives it. In order to calculate the pressure profile in advance (e.g. in simulation or in the engine control system), knowledge of the combustion duration or combustion profile and optionally other combustion parameters (e.g. center of gravity) is of crucial importance. The combustion engine can therefore be controlled based on the calculated pressure profile in order to set the adapted climate-neutral combustion duration and the adapted climate-neutral combustion profile during operation of the combustion engine and thus enable the most optimal operation possible.

[0041] The method may include a modification of a control system and / or a modified control of the internal combustion engine for operation with a climate-neutral fuel by controlling the internal combustion engine (and / or the at least one cylinder) to generate the calculated pressure curve. The method may include a modification of a control system and / or a modified control of the internal combustion engine for operation with a climate-neutral fuel, taking into account the adapted climate-neutral combustion duration and the adapted climate-neutral combustion curve.

[0042] Detecting the fossil combustion quantities may include retrieving the predetermined and / or stored fossil combustion quantities.

[0043] The fossil combustion variables may further include a fuel type and / or reaction kinetic and / or physical properties of the fossil fuel. The fossil combustion variables may include a temperature (or a temperature profile) and / or a pressure (or a pressure profile) of the fossil fuel.

[0044] Determining the climate-neutral combustion process and the climate-neutral combustion duration may include determining a conversion factor depending on the fossil combustion parameters and converting the fossil combustion duration into the climate-neutral combustion duration using the determined conversion factor (and optionally converting the fossil combustion process into the climate-neutral combustion duration, e.g. using the determined conversion factor).

[0045] The climate-neutral combustion process can be determined depending on the climate-neutral combustion duration (and optionally the fossil combustion duration), e.g., by scaling the fossil combustion process depending on the climate-neutral combustion duration.

[0046] Determining the conversion factor may comprise determining a fossil laminar flame speed of the fossil fuel and a climate-neutral laminar flame speed of the climate-neutral fuel as a function of the fossil combustion variables, wherein, for example, the fossil laminar flame speed and the climate-neutral laminar flame speed can be selected from a lookup table (or a tabular database).

[0047] The (fossil and / or climate-neutral) laminar flame speed can (e.g., in each case) depend on the crank angle of a cylinder of the internal combustion engine. The (fossil and / or climate-neutral) laminar flame speed can (e.g., in each case) be an average (fossil and / or climate-neutral) laminar flame speed (or an average value of a laminar flame speed profile) between two crank angles (or within a crank angle interval).

[0048] Determining the conversion factor may include calculating a flame speed ratio of the climate-neutral laminar flame speed to the fossil laminar flame speed and determining the conversion factor taking into account the calculated flame speed ratio.

[0049] Determining the conversion factor may include correcting the calculated flame speed ratio using a correction exponent and / or a correction factor. The determined conversion factor may correspond to the corrected flame speed ratio.

[0050] The correction exponent can be determined (or has been determined) by determining the correlation between the flame speed ratio and the ratio of the climate-neutral combustion duration to the fossil combustion duration using empirical data (or measurement data). The correlation determination can include a regression and / or a fit of a (e.g., polynomial or exponential) fit function.

[0051] The correction exponent can be applicable independently of the combustion engine and / or across combustion engines.

[0052] The determination of the climate-neutral combustion duration and the climate-neutral combustion process and / or the determination of conversion factors can be based on (e.g., predefined) empirical-physical (or physical) relationships (e.g., equations and / or correlations) and / or on the basis of reaction kinetic influences (or calculations).

[0053] Adjusting the climate-neutral burning time and the climate-neutral burning process may include determining an adjustment conversion factor depending on the determined climate-neutral burning time.

[0054] Adjusting the climate-neutral burning time and the climate-neutral burning process may include adjusting the fossil burning time by converting the determined climate-neutral burning time using the determined adjustment conversion factor (and optionally adjusting the fossil burning process by converting the determined climate-neutral burning process, e.g. using the determined adjustment conversion factor).

[0055] The climate-neutral combustion process can be adjusted depending on the adjusted climate-neutral combustion duration (and optionally the fossil combustion duration), e.g., by scaling the specific climate-neutral combustion process (or the fossil combustion duration) depending on the adjusted climate-neutral combustion duration.

[0056] Determining the adaptation conversion factor may include determining a first laminar flame speed of the climate-neutral fuel for the first air-fuel-water ratio and a second laminar flame speed of the climate-neutral fuel for the second air-fuel-water ratio, e.g., wherein the first laminar flame speed and the second laminar flame speed may be selected from a lookup table (or a tabular database).

[0057] The (first and / or second) laminar flame speed can (e.g., each) depend on a crank angle of a cylinder of the internal combustion engine. The (first and / or second) laminar flame speed can (e.g., each) be an average (first and / or second) laminar flame speed (or an average value of a laminar flame speed profile) between two crank angles (or within a crank angle interval).

[0058] Adjusting the climate-neutral combustion duration and the climate-neutral combustion process may comprise calculating an adjustment flame speed ratio of the second laminar flame speed to the first laminar flame speed and determining the adjustment conversion factor taking into account the calculated adjustment flame speed ratio.

[0059] Determining the adjustment conversion factor may include correcting the calculated adjustment flame speed ratio using an adjustment correction exponent.

[0060] The adjustment correction exponent can be determined (or be determined) by determining the correlation between the adjustment flame speed ratio and an adjustment combustion duration ratio of the combustion duration of the climate-neutral fuel with the second air-fuel-water ratio and the combustion duration of the climate-neutral fuel with the first air-fuel-water ratio based on empirical data (or measurement data). The correlation determination can include a regression and / or a fit of a (e.g., polynomial or exponential) fit function.

[0061] Adjusting the climate-neutral combustion duration and the climate-neutral combustion profile can include determining a second adjustment conversion factor depending on a first combustion center position during operation of the internal combustion engine with the climate-neutral fuel and the first air-fuel-water ratio and a second combustion center position during operation of the internal combustion engine with the climate-neutral fuel and the second air-fuel-water ratio. The first combustion center position and the second combustion center position can be determined, for example, based on empirical data (or measurement data). The (first and / or second) combustion center position can be a point in time at which 50% of the fuel used in the cycle has been combusted.

[0062] Adjusting the climate-neutral burning time and the climate-neutral burning process may include adjusting the fossil burning time by converting the determined climate-neutral burning time using the determined adjustment conversion factor and the determined second adjustment conversion factor.

[0063] The adjustment of the climate-neutral combustion duration and the climate-neutral combustion process may comprise calculating an adjustment combustion center position ratio of the second combustion center position to the first combustion center position and determining the second adjustment conversion factor taking into account the calculated adjustment combustion center position ratio.

[0064] Determining the second adjustment conversion factor may include correcting the calculated adjustment center of combustion ratio using a second adjustment correction exponent. The second adjustment correction exponent may be determined (or have been determined) by determining the correlation between the adjustment center of combustion ratio and the adjustment combustion duration ratio of the combustion duration of the climate-neutral fuel with the second air-fuel-water ratio and the combustion duration of the climate-neutral fuel with the first air-fuel-water ratio based on empirical data (or measured data). The correlation determination may include a regression and / or a fit of a (e.g., polynomial or exponential) fit function.

[0065] The adaptation correction exponent (and optionally the second adaptation correction exponent) can be applicable independently of the combustion engine and / or across combustion engines.

[0066] The adjustment of the climate-neutral burning duration and the climate-neutral burning process and / or the determination of the adjustment conversion factor can be carried out on the basis of (e.g., predefined) empirical-physical (or physical) relationships (e.g., equations and / or correlations) and / or on the basis of reaction kinetic influences (or calculations).

[0067] Furthermore, a device for data processing is provided which is designed to carry out the method described above at least partially, optionally completely.

[0068] It is conceivable that the device is a control device (or a control unit) for controlling an internal combustion engine for a motor vehicle. The device can also be referred to as an engine control unit. The device can, for example, be part of the motor vehicle. The control device can, for example, be an electronic control unit (ECU). The electronic control unit can be an intelligent processor-controlled unit that can communicate with other modules, for example, via a central gateway (CGW), and that can optionally form the vehicle's on-board network via fieldbuses such as the CAN bus, LIN bus, MOST bus, FlexRay, and / or via the automotive Ethernet, e.g., together with telematics control units. The motor vehicle can be a passenger car, in particular an automobile, or a commercial vehicle, such as a truck.

[0069] What has been described above with reference to the method also applies analogously to the device and vice versa.

[0070] Furthermore, a computer program is provided, comprising instructions which, when the program is executed by a computer, cause the computer to at least partially carry out or implement the method described above.

[0071] A program code of the computer program may be in any code, in particular in a code that is suitable for a data processing device, e.g. the device described above.

[0072] It is conceivable that the computer program can be a (e.g. 0- or 1-dimensional) flow simulation program and / or a (e.g. 1-dimensional) engine simulation program.

[0073] What has been described above with reference to the method and the device also applies analogously to the computer program and vice versa.

[0074] Furthermore, a computer-readable medium, in particular a computer-readable storage medium, is provided. The computer-readable medium comprises instructions which, when executed by a computer, cause the computer to at least partially execute the method described above.

[0075] That is, a computer-readable medium may be provided which comprises a computer program as defined above.

[0076] The computer-readable medium can be any digital data storage device, such as a USB stick, a hard disk, a CD-ROM, an SD card or an SSD card.

[0077] The computer program does not necessarily have to be stored on such a computer-readable storage medium to be made available to the computer, but can also be obtained via the Internet or some other external source. It can therefore also be a data signal.

[0078] What has been described above with reference to the method, the device and the computer program also applies analogously to the computer-readable medium and vice versa.

[0079] Below is an embodiment with reference to Fig. 1 to 4 described. Fig. 1 schematically shows a flow diagram of a method according to the disclosure for converting and / or using an internal combustion engine for operation with a climate-neutral fuel, Fig. 2 shows schematically exemplary combustion processes or a pressure profile during various steps of the disclosed method, Fig. 3 schematically shows an exemplary flow diagram of a second step of the method according to the disclosure, and Fig. 4 schematically shows an exemplary flow diagram of a third step of the method according to the disclosure.

[0080] The computer-implemented method 100 for converting and / or using an internal combustion engine, which is designed for operation with a fossil fuel, for operation with a climate-neutral fuel essentially comprises four steps S1, S2, S3 and S4, as shown in the flow chart in Fig. 1 is shown.

[0081] In the first step S1 of method 100, fossil combustion variables are recorded during operation of the internal combustion engine with the fossil fuel. The fossil combustion variables include a fossil combustion duration, a fossil combustion profile, and a first air-fuel-water ratio. The fossil combustion variables may further include, among other things, a fuel type (of the fossil fuel) and reaction kinetic and / or physical properties of the combustion of the fossil fuel, e.g., a pressure and / or temperature profile as a function of a crank angle of a cylinder of the internal combustion engine.

[0082] In the second step S2 of the method 100, a climate-neutral combustion duration and a climate-neutral combustion profile are determined when the internal combustion engine is operated with the climate-neutral fuel and the first air-fuel-water ratio based on the fossil combustion variables.

[0083] For this purpose, a conversion factor can be determined depending on the fossil combustion parameters and then the fossil combustion time can be converted into the climate-neutral combustion time based on the determined conversion factor.

[0084] The conversion factor can be determined, for example, by determining a fossil laminar flame speed of the fossil fuel and a climate-neutral laminar flame speed of the climate-neutral fuel as a function of the fossil combustion parameters and calculating a flame speed ratio of the climate-neutral laminar flame speed to the fossil laminar flame speed.

[0085] The calculated flame speed ratio can be corrected using a correction exponent and / or a correction factor. The correction exponent can be determined, for example, by determining a correlation between the flame speed ratio and a combustion duration ratio of the climate-neutral combustion duration to the fossil combustion duration based on empirical data.

[0086] The conversion factor can be determined accordingly taking into account the calculated flame speed ratio, whereby the determined conversion factor can, for example, correspond to the corrected flame speed ratio.

[0087] In the third step S3 of the method 100, the climate-neutral combustion duration is adapted to the fossil combustion duration and the climate-neutral combustion profile is adapted to the fossil combustion profile, wherein the first air-fuel-water ratio is changed to a second air-fuel-water ratio.

[0088] For this purpose, an adjustment conversion factor can be determined depending on the determined climate-neutral burning time and optionally the determined climate-neutral burning process, and then the fossil burning time can be adjusted by converting the determined climate-neutral burning time using the determined adjustment conversion factor.

[0089] The adjusted climate-neutral burning time (or the ratio of the adjusted climate-neutral burning time to the specific climate-neutral burning time, i.e. the ratio of the climate-neutral burning time after conversion to the climate-neutral burning time before conversion) can be used to adjust the climate-neutral burning process. For this purpose, the ratio of the adjusted climate-neutral burning time to the specific climate-neutral burning time or the inverse thereof can be applied as a scale to the x and y values ​​of the climate-neutral burning process. In this way, the climate-neutral burning time can quantitatively change the shape of the burning process in terms of compression or stretching, but not in terms of possible “anomalies” in the curve of the climate-neutral burning process. Anomalies in the burning process lead to the burning process being either symmetrical (in the vertical plane) or asymmetrical, whereby an asymmetrical curve, for example,For example, it can exhibit delayed burnout (i.e., a smaller gradient after a peak than before the peak). The combustion duration can therefore only be the quantitative tool for shaping the combustion process depending on the air-fuel-water ratio, fuel, etc.

[0090] For the (fossil and / or climate-neutral) combustion time, the combustion time from the time at which 10% of the fuel has been converted into energy (also: Q10) to the time at which 90% of the fuel has been converted into energy (also: Q90) can be used or considered. This combustion time is also referred to as BD1090. Alternatively, it is conceivable to use or consider the combustion time from the time at which 5% of the fuel has been converted into energy (also: Q05) to the time at which 95% of the fuel has been converted into energy (also: Q95), which is also referred to as BD0595.

[0091] An advantage of the combustion duration BD1090 (or BD0595) compared to the complete combustion duration (i.e., BD00100) is that the physically highly complex range of ignition delay time, in which the first approximately 2% of the fuel has been energetically converted (i.e., from Q00 to approximately Q02), is not taken into account, since this range is not relevant to the method of the present disclosure. Furthermore, it is not relevant whether the combustion is 100% complete (i.e., only up to Q99). The above-mentioned combustion durations BD1090 or BD0595 therefore focus only on the energetically relevant or quantitatively largest fuel conversion and the resulting impact on the pressure curve.

[0092] The adaptation conversion factor can be determined, for example, by determining a first laminar flame speed of the climate-neutral fuel for the first air-fuel-water ratio and a second laminar flame speed of the climate-neutral fuel for the second air-fuel-water ratio, and calculating an adaptation flame speed ratio of the second laminar flame speed to the first laminar flame speed.

[0093] The calculated adaptation flame speed ratio can be corrected using an adaptation correction exponent, wherein the adaptation correction exponent can be determined, for example, by determining a correlation between the adaptation flame speed ratio and an adaptation combustion duration ratio of the combustion duration of the climate-neutral fuel with the second air-fuel-water ratio and the combustion duration of the climate-neutral fuel with the first air-fuel-water ratio based on empirical data.

[0094] The adjustment conversion factor can be determined accordingly taking into account the calculated adjustment flame speed ratio, e.g. the corrected adjustment flame speed ratio.

[0095] Furthermore, additional adjustment conversion factors can be considered to adjust the climate-neutral combustion duration and the climate-neutral combustion profile. For example, a second adjustment conversion factor can be determined depending on a first combustion center position during operation of the internal combustion engine with the climate-neutral fuel and the first air-fuel-water ratio and a second combustion center position during operation of the internal combustion engine with the climate-neutral fuel and the second air-fuel-water ratio. Thus, the determined climate-neutral combustion duration can be adjusted based on the determined adjustment conversion factor and the determined second adjustment conversion factor (and optionally additional adjustment conversion factors).

[0096] Finally, in the fourth step S4 of the method 100, at least one parameter and / or at least one control signal for controlling the internal combustion engine for operation with the climate-neutral fuel is output as a function of the adapted climate-neutral combustion duration and the adapted climate-neutral combustion profile.

[0097] The at least one parameter can, for example, comprise a pressure profile of at least one cylinder of the internal combustion engine. Accordingly, the fourth step S4 can comprise calculating the pressure profile for the adjusted climate-neutral combustion duration and the adjusted climate-neutral combustion profile, and subsequently outputting the calculated pressure profile and / or at least one control signal depending on the calculated pressure profile.

[0098] Thus, the at least one output parameter (e.g. the pressure curve) or the at least one output control signal can be used to control the combustion engine and thus to be able to use or operate it for modified operation with the climate-neutral fuel instead of the fossil fuel.

[0099] Purely as an example, the Fig. 2 different combustion curves for steps S1, S2 and S3 and a pressure curve for step S4 of method 100. The combustion curves and the pressure curve can each be detected or determined as a function of a crank angle of a cylinder of the internal combustion engine.

[0100] In the first step S1, the fossil combustion profile A for operation with the fossil fuel is recorded, among other things. In the second step S2, the climate-neutral combustion profile B is determined using the climate-neutral fuel. The fuel composition of the climate-neutral fuel, with air and water, has the same initial air-fuel-water ratio as the fossil fuel, which leads to differences between the two combustion profiles A and B. For example, combustion profile B may have a higher maximum than combustion profile A.

[0101] In the third step S3, among other things, the climate-neutral combustion profile B is adapted to the fossil combustion profile A, so that the adapted climate-neutral combustion profile C has a profile or shape that is as close as possible to the fossil combustion profile A and is ideally identical to the fossil combustion profile A. The fuel composition of the climate-neutral fuel for the adapted climate-neutral combustion profile C has a second air-fuel-water ratio that differs from the first air-fuel-water ratio, for example, by being lower than the first air-fuel-water ratio.

[0102] Based on the adapted climate-neutral combustion profile C and the adapted climate-neutral combustion duration, the combustion engine can finally be converted for operation with the climate-neutral fuel by, among other things, calculating the pressure curve D of a cylinder of the combustion engine and applying it to the cylinder during operation of the combustion engine. The adapted climate-neutral combustion profile C or its direct specification is also already relevant in the preliminary development of the combustion engine, where the pressure curve D is calculated in a corresponding engine simulation and taken into account in the simulation.

[0103] Fig. 3 shows an exemplary flow chart for the second step S2, ie for determining the climate-neutral combustion duration and the climate-neutral combustion profile with a constant first air-fuel-water ratio.

[0104] Thus, the method 100 enables the continued use of existing combustion parameters or combustion variables, ie the combustion variables mentioned above, of the existing combustion engine for further development for the use of climate-neutral fuels, e.g., hydrogen and ammonia, but also e-fuels. Fig. 3 the fossil fuel is used as reference fuel ref and the climate-neutral fuel as a new fuel neu taken into account.

[0105] Physical influences of the specific fuel composition based on reaction kinetic calculations can be used to determine the flame speed (or combustion speed) of the respective fuel or fuel composition. The reaction kinetic calculations can take into account combustion variables, e.g., input information on the fuel type, a pressure profile, a temperature profile, an air / fuel ratio λ (or an inverse thereof, namely an equivalence ratio φ), and / or a mass- or molecule-related water content x. H2O The result can be the laminar flame speeds SL. These can be retrieved from a lookup table or a tabular database depending on the combustion parameters and fed into the further process 100.

[0106] It is conceivable that the physical relationships could be validated using measurement data from engine test benches of a new combustion engine that has been converted to use the new, climate-neutral fuel. The measurement data could, for example, contain data on specific variations of the fuel. For example, a natural gas engine (fuel ref ) for operation with hydrogen (fuel neu ). The measurement results, especially combustion profiles and durations, before and after the conversion can be compared, and empirical conversion correlations depending on the respective fuel composition can be established based on the measurement results. The results and derived empirical correlations can be used to validate and adjust the physical influences of the above-mentioned calculations, e.g., to calculate the laminar flame speeds (SL).

[0107] With the calculations and the optional measurements, an empirical-physical conversion approach according to the second step S2 of the method 100 can be developed, which enables a conversion or conversion of the combustion process and combustion duration (and optionally other combustion variables) from the fossil fuel to the climate-neutral fuel.

[0108] This empirical-physical conversion approach represents a semi-predictive approach which, unlike known non-predictive and predictive approaches, does not require new measurement results from a test bench using new (climate-neutral) fuels. The conversion approach, i.e., the second step S2, can be applied to an existing reference combustion profile (abbreviated to "ref") of the reference combustion engine to be converted for the fossil fuel. Specifically, a conversion factor (or conversion factor) derived from the conversion approach can be determined. The conversion factor can, for example, be applied to an x-axis (or y-axis) of the combustion profile, and the inverse of the conversion factor can be applied to the y-axis (or x-axis). This allows the combustion profile to be converted or reshaped according to the influence of the fuel. This results in the new combustion duration or the new combustion profile (abbreviated to "new") for the climate-neutral fuel.

[0109] Specifically, the conversion factor can be derived by comparing the combustion times of the fossil fuel and the new climate-neutral fuel. The resulting quotient can correspond to the conversion factor.

[0110] Using a (SL) lookup table, the profile of the laminar flame speed SL over a crank angle (CA), i.e. over the engine cycle and / or the combustion or expansion phase, can be output. Since for further calculations, not the entire profile of the laminar flame speed SL, but a specific quantitative value SL¯, If a mean value of the laminar flame speed SL is used, a curve between two crank angles (KW1 and KW2) can be averaged. The values ​​for KW1 = -10°KW (near top dead center) and KW2 = 45°KW (near top dead center) have been identified as possible reasonable angle values ​​after numerous comparisons. Fig. 2 this as SL¯ between week 1 and week 2.

[0111] To increase the prediction quality of the physical influences considered in the calculations and to improve the validation results of the measurements, the results of the laminar flame speed(s), for example, can be adjusted based on the known error rate in the engine-extrapolated pressure and temperature range. One possible adjustment is to select the reaction mechanism for each fuel for the entire range of pressure, temperature, equivalence ratio, and water content. Another possible adjustment is to combine several reaction mechanisms or their results in order to use the reaction mechanisms for specific subranges of pressure, temperature, equivalence ratio, and water content that have been optimized or created for the corresponding ranges or that demonstrate optimal results in terms of prediction quality and validation.

[0112] In general, a quotient of motor-relevant parameters, provided they have a relevant, causal, physical influence on the burning time, can be related to obtain the conversion factor for the burning time or the burning process: rParameter=ParameternewParameterref.

[0113] To determine the correlation function of an exemplary conversion factor x KONVEmpirical measurement data from the combustion engine can be used with an engine test bench to correlate a combustion variable or a physical parameter A, which is to be converted into a new combustion duration correlation, with the combustion duration. Measurement results for combustion duration and the specific parameter A can be recorded at different measurement points or engine operating points. To exclude cross-influences, the measurement points can be created under constant boundary conditions (center of gravity, combustion air ratio, injection timing, intake temperature, etc.). In particular, combustion variables or parameters that have a known, clear influence on the combustion duration (combustion air ratio, center of gravity, etc.) should not change or should change only minimally between the measurement points. If n measurement points (without relevant cross-influences) are available, n 2-n combinations are available. This can make the conversion approach very effective, as only a few measurement points need to be available. For example, with 10 measurement points, 90 combinations are available to test the correlation. Specifically, xParameter A=BDnewBDref and rParameter A=ParameternewParameterref be correlated by a regression (a so-called fit). The regression or fitting function (e.g., polynomial, exponential, etc.) can be chosen so that the R 2 -value is as close to 1 as possible.

[0114] In the present case, in the second step S2, the parameter A can be the mean value of the laminar flame speed SL¯ act so that the quotient rSL=SL¯newSL¯ref and based on the measured data and the regression the conversion factor x KONV = r SL c can be determined.

[0115] This results in the conversion formula for step S2 to determine the climate-neutral burning time BD neu from the fossil burning time BD ref : BDnew=BDref⋅xKONV⋅fadj

[0116] Specific values ​​and the fitting function(s) can be determined, for example, using the procedure described above. The specific correlation values ​​of the fitting function(s) can be generally applicable through the physical coupling of the empirical data, i.e., applicable across combustion engines. For very different combustion engines, e.g., large-displacement engines for trucks and high-revving sports engines for cars, an adjustment of the correlation values ​​may be useful or necessary. This can be the case if the correlation was initially established with a combustion engine that lies at the edge of the classic engine spectrum, e.g., with a cylinder volume between 0.3 L and 2.5 L per cylinder. Displacement-dependent effects such as global charge movement, a magnitude of turbulent kinetic energy, a compression ratio, etc., can cause the deviation.However, these effects can also be accounted for using the conversion approach. Alternatively, the factor f can be used for (e.g., manual) adjustment. adj which, for example, lies between 0.9 and 1.1.

[0117] Fig. Figure 4 shows an exemplary flow chart for the third step S3, i.e., for adjusting the climate-neutral combustion duration and the climate-neutral combustion profile with the changed second air-fuel-water ratio. The fuel thus remains the same in this step S3, but the fuel composition changes. The climate-neutral fuel with the first air-fuel-water ratio is Fig. 4 is considered as the reference fuel (ref for short), while the climate-neutral fuel with the second air-fuel-water ratio is considered as the new fuel (new for short).

[0118] Analogous to the procedure described above, physical influences of the specific mixture or fuel composition based on reaction kinetic calculations regarding the air-to-fuel or air-to-fuel-to-water ratios can be used to determine a flame speed or combustion speed. These flame speeds can also be retrieved from a lookup table or a tabular database depending on the combustion parameters and further used.

[0119] Here, too, it is conceivable that the physical relationships could be validated using measurement data from engine test benches of a new combustion engine that has been converted to use the new, climate-neutral fuel. This allows measurement data to be generated by varying the air-fuel ratio or the air-fuel-water ratio. The water content can be determined from exhaust gas recirculation, in which a portion (e.g., 0% to 40% based on the total mass flow) of the combusted fuel mixture is taken downstream of the combustion chamber and added to the unburned fresh air upstream of the combustion chamber. Likewise, the water content can be increased by water injection through a separate injector upstream of the combustion chamber. Furthermore, if the ambient air is not dry, the water content dissolved in this air can be greater than 0% (air humidity) based on the total mass flow.This allows empirical conversion correlations to be established depending on the air-fuel ratio or the air-fuel-water ratio. The results and derived empirical correlations can be used to validate and adjust the physical influences.

[0120] Similar to the second step S2, the calculations and optional measurements can result in an empirical-physical (adaptation) conversion approach according to the third step S3 of the method 100, which enables a conversion or recalculation of the combustion profile and combustion duration (and optionally other combustion variables) of the climate-neutral fuel from the first air-fuel-water ratio to the second air-fuel-water ratio. This allows, for example, a dilution of the fuel mixture and its effect on the combustion duration and combustion profile to be mapped as precisely and robustly as possible.

[0121] The empirical-physical (adaptation) conversion approach also represents a semi-predictive approach that does not require new measurement results from a test bench with new (climate-neutral) fuels. The (adaptation) conversion approach, i.e., the third step S3, can be applied to the previously determined reference combustion duration or combustion profile (abbreviated to "ref") for operation with the climate-neutral fuel with the first air-fuel-water ratio. Specifically, an (adaptation) conversion factor (or (adaptation) conversion factor) derived from the conversion approach can be determined, so that the combustion duration or combustion profile can be converted or recalculated according to the influence of the air-fuel-water ratio. This can result in the new combustion duration or combustion profile (abbreviated to "new").

[0122] Specifically, the (adjustment) conversion factor can be derived by comparing the combustion times for the climate-neutral fuel with the different fuel-water ratios. The resulting quotient can correspond to the (adjustment) conversion factor.

[0123] Analogous to the procedure in the second step S2, in the third step S3, using the SL lookup table, an average value of the laminar flame speed SL¯ between two crank angles KW1 and KW2, e.g., for an interval between KW1= -10°KW (near top dead center) and KW2= 45°KW (near top dead center). Fig. 3 this is indicated as SL between KW1 and KW2.

[0124] Here too, a quotient rSL=SL¯newSL¯ref be set up, whereby SL¯ref the average flame speed of the climate-neutral fuel, the first air-fuel-water ratio and SL¯new the average flame speed of the climate-neutral fuel with the second air-fuel-water ratio.

[0125] To determine the correlation function of an exemplary adjustment conversion factor x DIL-KONVHere, empirical measurement data from the combustion engine can also be used with an engine test bench to correlate the existing physical parameter, i.e., the average flame speed, with the combustion duration. Measurement results for combustion duration and the average flame speed can be recorded at different measurement points or engine operating points, whereby the measurement points are created under constant boundary conditions (center of gravity, combustion air ratio, injection timing, intake temperature, etc.). Thus, as previously described, a regression or fitting (e.g., polynomial, exponential, etc.) can be carried out, so that in the third step S3, the quotient rSL=SL¯newSL¯ref and based on the measured data and the regression, the adjustment conversion factor x DIL-KONV = r SL a can be determined.

[0126] Additionally, using measurement data, an empirical correlation can be created depending on the parameter Q50 (i.e., the point in time at which 50% of the fuel used in the cycle has been combusted). This allows the influence of a change in the center of gravity position on the combustion process and duration to be mapped. This can be particularly advantageous because the center of gravity position has a significant influence on the shape of the combustion process and, accordingly, on the combustion duration. Accordingly, the center of gravity position correlation can be used, for example, to eliminate the influence of the center of gravity position in sensitivity studies of other parameters, thus minimizing cross-influences.

[0127] Analogous to the adjustment conversion factor x DIL-KONV can be a quotient rQ50=Q50newQ50ref with the combustion center Q50 reffor the climate-neutral fuel with the first air-fuel-water ratio and with the combustion center Q50 neu for the climate-neutral fuel with the second air-fuel-water ratio and, based on a regression, a further, second adjustment conversion factor (or a combustion center conversion factor) x Q50 = r Q50 b For example, regression or fitting can determine x Q50 = r Q50 0,0616 result.

[0128] Since the new combustion center of gravity position may differ from the reference center of gravity position after the conversion, a PID control can be implemented, for example when used in a 0D / 1D simulation program or in a control system on the test bench or in an engine control unit, in order to achieve the center of gravity position of the reference using the manipulated variable "ignition timing".

[0129] Furthermore, it should be noted that it was found that the combustion profile of a specific internal combustion engine can be quantitatively described or scaled using the combustion duration and its magnitude. Characteristic profiles and irregularities in the combustion profile, deviating from the perfectly symmetrical combustion profile of a gasoline engine, can be contained in the combustion profile of the specific internal combustion engine. The characteristic profiles of the combustion profile of the specific reference internal combustion engine, i.e., the internal combustion engine designed for operation with liquid fuel, can therefore be taken into account even after scaling using the present (adaptation) conversion approach, thus delivering robust and realistic results.

[0130] For example, after a series of measurements on a specific combustion engine, a purely empirical combustion duration correlation can be created, which can be used to predict combustion durations and thus also combustion profiles at different measurement points of the same combustion engine. The combustion duration can be specifically determined, for example, as a function of the combustion air ratio λ, the water content x H2O or the center of gravity Q50, e.g., x DIL = f(λ, x H2O ). Other values ​​are conceivable as long as they significantly influence the burning time. This can, for example, result in an additional conversion factor xDIL=BDDIL,newBDDIL,ref result.

[0131] Thus, for example, the conversion formula for the third step S3 for adapting the climate-neutral burning time to the previously recorded fossil burning time is obtained by converting the climate-neutral burning time BD neuwith the second air-fuel-water ratio from the climate-neutral combustion duration BD ref with the first air-fuel-water ratio: BDneu=BDref⋅xDIL−KONV⋅xQ50⋅fadj

[0132] The conversion formula can be supplemented with additional conversion factors to also semi-predictively consider or represent additional engine parameters. The process for expanding with additional conversion factors can be carried out analogously to the process using the mean flame speed as a parameter.

[0133] Analogous to the second step S2, in this third step S3, concrete values ​​and the fitting function(s) can be determined using the procedure described above. The concrete correlation values ​​of the fitting function(s) can be generally applicable, i.e., across combustion engines, due to the physical coupling of the empirical data. Combustion engine-dependent effects, e.g., displacement-dependent effects, can be mapped using the conversion approach, if necessary, or alternatively, the factor f adj which, for example, lies between 0.9 and 1.1. List of reference symbols 100 procedures S1-S4 process steps A, B, C firing sequences D Pressure curve

Claims

[1] Computer-implemented method (100) for converting and / or using an internal combustion engine designed for operation with a fossil fuel for operation with a climate-neutral fuel, characterized by that the method (100) comprises: - detecting (S1) fossil combustion variables during operation of the internal combustion engine with the fossil fuel, wherein the fossil combustion variables include a fossil combustion duration, a fossil combustion profile and a first air-fuel-water ratio; - Determining (S2) a climate-neutral combustion duration and a climate-neutral combustion profile when operating the internal combustion engine with the climate-neutral fuel and the first air-fuel-water ratio based on the fossil combustion parameters; - adapting (S3) the climate-neutral combustion duration to the fossil combustion duration and the climate-neutral combustion profile to the fossil combustion profile, wherein the first air-fuel-water ratio is changed to a second air-fuel-water ratio; and - Outputting (S4) at least one parameter and / or at least one control signal for controlling the internal combustion engine for operation with the climate-neutral fuel as a function of the adapted climate-neutral combustion duration and the adapted climate-neutral combustion profile, wherein the climate-neutral fuel is a CO2-neutral fuel or a CO2-free fuel and comprises or consists of hydrogen, ammonia and / or a synthetic hydrocarbon. [2] Computer-implemented method (100) according to claim 1, characterized bythat the at least one parameter comprises a pressure curve of at least one cylinder of the internal combustion engine, and the output (S4) of the at least one parameter and / or the at least one control signal comprises: - Calculating the pressure curve for the adjusted climate-neutral burning time and the adjusted climate-neutral burning curve; and - Outputting (S4) the calculated pressure curve and / or at least one control signal as a function of the calculated pressure curve. [3] Computer-implemented method (100) according to claim 1 or 2, characterized by that the fossil combustion variables further include a fuel type and reaction kinetic and / or physical properties of the fossil fuel. [4] Computer-implemented method (100) according to one of claims 1 to 3, characterized by that the determination (S2) of the climate-neutral burning process and the climate-neutral burning duration includes: - Determination of a conversion factor depending on the fossil combustion parameters; and - Converting the fossil burning time into the climate-neutral burning time using the determined conversion factor. [5] Computer-implemented method (100) according to claim 4, characterized by that determining the conversion factor includes: - Determining a fossil laminar flame speed of the fossil fuel and a climate-neutral laminar flame speed of the climate-neutral fuel as a function of the fossil combustion parameters; - Calculating a flame speed ratio of the climate-neutral laminar flame speed to the fossil laminar flame speed; and - Determine the conversion factor taking into account the calculated flame speed ratio. [6] Computer-implemented method (100) according to claim 5, characterized bythat determining the conversion factor includes: - Correcting the calculated flame speed ratio using a correction exponent and / or a correction factor, whereby the determined conversion factor corresponds to the corrected flame speed ratio. [7] Computer-implemented method (100) according to claim 6, characterized by , that - the correction exponent is determined by a correlation determination between the flame speed ratio and a combustion duration ratio of the climate-neutral combustion duration to the fossil combustion duration based on empirical data, and / or - the correction exponent is applicable independently of the combustion engine and / or across combustion engines. [8] Computer-implemented method (100) according to one of claims 1 to 7, characterized by that the adjustment (S3) of the climate-neutral burning time and the climate-neutral burning process includes: - Determining an adjustment conversion factor depending on the determined climate-neutral burning time; and - Adjusting the fossil burning time by converting the determined climate-neutral burning time using the determined adjustment conversion factor. [9] Computer-implemented (100) method according to claim 8, characterized by that determining the adjustment conversion factor includes: - determining a first laminar flame speed of the climate-neutral fuel for the first air-fuel-water ratio and a second laminar flame speed of the climate-neutral fuel for the second air-fuel-water ratio; - calculating an adjustment flame speed ratio of the second laminar flame speed to the first laminar flame speed; and - Determine the adjustment conversion factor taking into account the calculated adjustment flame speed ratio. [10] Computer-implemented method (100) according to claim 9, characterized by that determining the adjustment conversion factor includes: - Correcting the calculated adjustment flame speed ratio using an adjustment correction exponent, optionally - the adaptation correction exponent is determined by a correlation determination between the adaptation flame speed ratio and an adaptation combustion duration ratio of the combustion duration of the climate-neutral fuel with the second air-fuel-water ratio and the combustion duration of the climate-neutral fuel with the first air-fuel-water ratio based on empirical data, and / or - the adaptation correction exponent is applicable independently of the combustion engine and / or across combustion engines. [11] Computer-implemented method (100) according to one of claims 8 to 10, characterized by that the adjustment (S3) of the climate-neutral burning time and the climate-neutral burning process includes: - determining a second adaptation conversion factor as a function of a first combustion center position during operation of the internal combustion engine with the climate-neutral fuel and the first air-fuel-water ratio and a second combustion center position during operation of the internal combustion engine with the climate-neutral fuel and the second air-fuel-water ratio; and - Adjusting the fossil burning time by converting the determined climate-neutral burning time using the determined adjustment conversion factor and the determined second adjustment conversion factor. [12] Device for data processing, characterized bythat the device is designed to carry out the method (100) according to one of claims 1 to 11. [13] Device according to claim 12, characterized by that the device is a control device for controlling an internal combustion engine for a motor vehicle. [14] Computer program, characterized by that the computer program comprises instructions which, when the program is executed by a computer, cause the computer to carry out the method (100) according to one of claims 1 to 11. [15] Computer-readable medium, characterized by that the computer-readable medium comprises instructions which, when executed by a computer, cause the computer to carry out the method (100) according to any one of claims 1 to 11.

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