Method and device for operating an internal combustion engine

Abstract

The invention relates to a device for operating an internal combustion engine with a fuel. The device is set up to determine a standard ignition angle for an actual operating point of the internal combustion engine on the basis of ignition angle characteristic data, and to determine a knock limit distance of the standard ignition angle from a knock limit of the internal combustion engine on the basis of knock limit distance characteristic data for the actual operating point of the internal combustion engine. The device is also set up to determine an operating ignition angle for the operation of the combustion engine and / or an actual RON value of the fuel on the basis of the standard ignition angle and on the basis of the knock limit distance.

Description

[0001] Method and device for operating an internal combustion engine

[0002] The invention relates to a method and a corresponding device designed to determine the ignition angle for the operation, in particular for the pre-control, of an internal combustion engine.

[0003] The internal combustion engine, particularly a gasoline engine, of a vehicle is preferably operated as close as possible to the knock limit in order to optimize the efficiency of the internal combustion engine. The knock limit typically depends on the quality, particularly the RON number (octane rating), of the fuel. A high-quality fuel with a relatively high RON number enables knock-free operation of the internal combustion engine with a relatively advanced ignition timing (i.e., with a relatively "early" ignition angle), thereby increasing the efficiency of the internal combustion engine.

[0004] To determine the earliest possible ignition timing or ignition angle that enables knock-free operation of the internal combustion engine, a previously determined ignition angle map (e.g., experimentally and / or based on simulations) can be used. The ignition angle map can be determined for a fuel with a relatively high RON number. Furthermore, the ignition angle map can be determined for a specific standard temperature (e.g., of the fuel, the intake air, the coolant, and / or the immediate surroundings of the combustion chamber). In general, the ignition angle map can be determined for one or more standard boundary conditions. Each of the one or more standard boundary conditions can alternatively be referred to as a design boundary condition (since the ignition angle map was designed for these one or more boundary conditions).

[0005] If the vehicle is running on fuel with a lower actual RON number (below the standard RON number for which the ignition angle map was designed), a knock path adaptation can be used to determine a delta to correct the ignition angle specified in the ignition angle map. Furthermore, a temperature model can be used to determine an offset value to correct the ignition angle specified in the ignition angle map if the actual fuel temperature deviates from the standard temperature (particularly if the actual temperature (e.g. of the fuel, the intake air, the coolant and / or the immediate surroundings of the combustion chamber) is higher than the standard temperature).

[0006] It is expected that the quality, i.e. the RON number, of available fuels will continue to increase, whereby the increased RON number should be used as the standard RON number for the ignition timing map in order to be able to utilize the increased efficiency of the internal combustion engine made possible by the increased fuel quality in an efficient manner.

[0007] However, it has been shown that the ignition timing map for a fuel with such a high RON number (e.g., RON > 100) at standard temperature (e.g., at 20°C) can no longer be determined experimentally at all operating points. In particular, at certain operating points, it is no longer possible (e.g., due to restrictions on the maximum permissible operating pressure and / or the maximum permissible operating temperature of the combustion engine) to set the ignition timing or ignition angle sufficiently advanced to reach the knock limit.

[0008] The ignition angle characteristic determined for a fuel with a particularly high RON number thus indicates ignition angles at certain operating points (particularly for a relatively high engine load) that are determined by the operating limits (in relation to the operating pressure and / or operating temperature) of the internal combustion engine and that do not correspond to the earliest possible ignition angle at the knock limit. As a result, the internal combustion engine cannot be operated with optimal efficiency at the specific operating points, even if the actual fuel conditions (in particular the actual temperature (e.g., of the fuel, the intake air, the coolant, and / or the immediate environment of the combustion chamber)) deviate from the standard boundary conditions (in particular from the standard temperature).

[0009] This document deals with the technical task of enabling efficiency-optimised operation of an internal combustion engine even with fuels with a particularly high RON number, in particular when the actual one or more boundary conditions deviate from the standard boundary conditions (for which the ignition angle map was determined).

[0010] The problem is solved by each of the independent claims. Advantageous embodiments are described, among other things, in the dependent claims. It should be noted that additional features of a patent claim dependent on an independent patent claim can form a separate invention, independent of the combination of all features of the independent patent claim, without the features of the independent patent claim or only in combination with a subset of the features of the independent patent claim, which invention can be made the subject of an independent claim, a divisional application, or a subsequent application. This applies equally to technical teachings described in the description, which can form an invention independent of the features of the independent patent claims.

[0011] According to one aspect, a device for operating an internal combustion engine (in particular a spark-ignition engine) with a fuel (in particular gasoline) is described. The fuel has an actual RON value. The device can be designed to determine the operating ignition angle with which the internal combustion engine can be operated in the most efficient manner possible when using the fuel with the actual RON value. The operating ignition angle can be used for the pre-control (of the ignition angle) of the internal combustion engine (in particular the ignition angle control of the internal combustion engine).

[0012] The device is configured to determine a standard ignition angle based on ignition angle characteristic data for the (currently existing) actual operating point of the internal combustion engine. The actual operating point can be defined by a combination of an actual load and an actual speed. The ignition angle characteristic data can specify the standard ignition angle for a large number of different possible operating points. The ignition angle characteristic data can be determined experimentally and / or based on simulations prior to operation of the internal combustion engine. If necessary, different ignition angle characteristic data can be provided for different operating modes of the internal combustion engine (e.g. Valvetronic operation (load control via valve lift), standard operation, throttled operation, Miller operation, etc.). The ignition angle characteristic data can be based on one or more standard boundary conditions for the operation of the internal combustion engine.Examples of standard boundary conditions are a standard temperature (e.g. of the fuel, the intake air, the coolant and / or the direct environment of the combustion chamber) and / or a standard lambda value (i.e. a standard ratio of the amount of combustion air to the amount of fuel in the combustion chamber of the internal combustion engine).

[0013] Furthermore, the ignition angle characteristics can be based on the operation of the internal combustion engine with fuel having a standard RON value. The standard RON value can alternatively also be referred to as the design RON value, since the ignition angle characteristics were designed for the standard RON value (i.e., for the design RON value). The ignition angle characteristics can have been determined with the aim of providing a standard ignition angle for each of the numerous possible operating points of the internal combustion engine, which lies at the knock limit of the internal combustion engine (given the presence of one or more standard boundary conditions).The ignition angle characteristics can thus have been determined in such a way that the ignition angle characteristics for the individual operating points, as far as possible, indicate the ignition angle which, when using a fuel with the standard RON value and when one or more standard boundary conditions are present, is directly at the knock limit of the internal combustion engine and / or which enables efficiency-optimised operation of the internal combustion engine.

[0014] However, the standard RON value may be so high that, due to one or more physical limit values ​​of the internal combustion engine (e.g., a pressure limit value and / or a temperature limit value), the ignition angle characteristic data for at least some of the plurality of possible operating points each indicate a standard ignition angle that has an ignition angle delta from the knock limit of the internal combustion engine (given the presence of the one or more standard boundary conditions). In other words, it may be that when using a fuel with a relatively high standard RON value (e.g., RON>100), the internal combustion engine cannot be operated directly at the knock limit for at least some of the possible operating points (in particular at a relatively high engine load).As a consequence, the ignition angle characteristics for this part of the possible operating points do not indicate the respective ignition angle at the knock limit, but rather an ignition angle that is away from the knock limit by a certain ignition angle delta.

[0015] The device is further configured to determine, based on knock limit distance characteristic data for the actual operating point of the internal combustion engine, a knock limit distance (in particular an ignition angle delta) between the standard ignition angle and the knock limit of the internal combustion engine. The knock limit distance can indicate the ignition angle delta by which the standard ignition angle deviates from the knock limit of the internal combustion engine at the actual operating point of the internal combustion engine (given the presence of one or more actual boundary conditions or the presence of one or more standard boundary conditions) (and by which the standard ignition angle could be further advanced before the knock limit of the internal combustion engine is reached).

[0016] The knock limit distance characteristic data can indicate the knock limit distance for the numerous possible operating points of the internal combustion engine. The knock limit distance characteristic data can be determined experimentally and / or based on simulations prior to the operation of the internal combustion engine. If necessary, different knock limit distance characteristic data can be provided for different operating modes of the internal combustion engine (e.g., Valvetronic operation (load control via valve lift), conventional operation, throttled operation, Miller operation, etc.).

[0017] The device can be set up to determine the knock limit distance of the standard

[0018] The ignition angle is determined from the knock limit of the internal combustion engine as a function of one or more actual boundary conditions, in particular as a function of the deviation of one or more actual boundary conditions from one or more corresponding standard boundary conditions. This allows the knock limit distance to be determined particularly precisely.

[0019] Furthermore, the device is configured to determine the operating ignition angle for the operation of the internal combustion engine and / or the actual RON value of the fuel based on the standard ignition angle and the knock limit. By taking into account a knock limit, which depends on the ignition angle delta of the standard ignition angle and the knock limit of the internal combustion engine, efficiency-optimized operation of the internal combustion engine can be achieved efficiently and reliably, even with particularly high-quality fuels (with a particularly high actual RON value) (at least when the one or more actual boundary conditions deviate from the one or more corresponding standard boundary conditions).

[0020] The device can be configured to determine the one or more (currently existing) actual boundary conditions for the operation of the internal combustion engine, wherein the one or more actual boundary conditions deviate at least partially from the one or more corresponding standard boundary conditions. An offset value can then be determined using a correction unit, in particular a model-based one, and based on the one or more actual boundary conditions. The operating ignition angle for the operation of the internal combustion engine and / or the actual RON value of the fuel can then also be determined in a particularly precise manner based on the offset value. This allows the efficiency of the internal combustion engine to be further increased.

[0021] The device can be configured to use knock path adaptation (e.g., using knock control) to determine an adaptation ignition angle delta of the standard ignition angle from the knock limit of the internal combustion engine (given the presence of one or more actual boundary conditions). In doing so, the knock path adaptation can take into account one or more limit values ​​of the internal combustion engine. In particular, the knock path adaptation can ensure that one or more limit values ​​of the internal combustion engine are not exceeded. This can (when using a fuel with a relatively high actual RON value) lead to the actual knock limit of the internal combustion engine not being reached during the knock path adaptation.

[0022] The operating ignition angle for the operation of the combustion engine and / or the actual RON value of the fuel can also be determined particularly precisely based on the adaptation ignition angle delta. The device can be configured, in particular, to reduce the standard RON value by a first delta RON value dependent on the adaptation ignition angle delta and to increase it by a second delta RON value dependent on the knock limit in order to determine the actual RON value of the fuel. The actual RON value of the fuel can thus be determined particularly precisely.

[0023] The device can thus be configured to determine the actual RON value of the fuel used to operate the internal combustion engine. The actual RON value can be compared with an RON threshold value (whereby the RON threshold value may be different for different operating points of the internal combustion engine). Depending on the comparison, a decision can then be made as to whether or not the knock limit distance is taken into account when determining the operating ignition angle. In particular, the device can be configured to take the knock limit distance into account when determining the operating ignition angle, in particular to only take it into account if the actual RON value is equal to or greater than the RON threshold value. In this way, the reliability of the operation of the internal combustion engine (particularly with regard to knock-free operation of the internal combustion engine) can be further increased in an efficiency-optimized manner.According to a further aspect, a (road) motor vehicle (in particular a passenger car or a truck or a bus or a motorcycle) is described which comprises the device described in this document.

[0024] According to a further aspect, a method for operating an internal combustion engine with a fuel (in particular gasoline) is described. The method comprises determining, based on ignition angle characteristics, a standard ignition angle for an actual operating point of the internal combustion engine, and determining, based on knock limit characteristic data and for the actual operating point of the internal combustion engine, a knock limit distance of the standard ignition angle from the knock limit of the internal combustion engine. Furthermore, the method comprises determining the operating ignition angle for the operation of the internal combustion engine and / or the actual RON value of the fuel based on the standard ignition angle and the knock limit distance.

[0025] According to another aspect, a software (SW) program is described. The SW program can be configured to be executed on a processor (e.g., on a vehicle control unit) and thereby to carry out the method described in this document.

[0026] According to a further aspect, a storage medium is described. The storage medium can comprise a software program configured to be executed on a processor and thereby to carry out the method described in this document.

[0027] It should be noted that the methods, devices, and systems described in this document can be used both alone and in combination with other methods, devices, and systems described in this document. Furthermore, any aspects of the methods, devices, and systems described in this document can be combined in a variety of ways. In particular, the features of the claims can be combined in a variety of ways. Furthermore, features listed in parentheses are to be understood as optional features.

[0028] The invention will be described in more detail below using exemplary embodiments.

[0029] Figure 1a shows exemplary components of a vehicle with an internal combustion engine;

[0030] Figure 1b shows an exemplary ignition angle map;

[0031] Figure 1c shows an exemplary device for determining the ignition angle or ignition timing for the operation of an internal combustion engine;

[0032] Figure 2 shows a device for determining the ignition angle or the ignition point for the operation of an internal combustion engine, taking into account fuels with a particularly high RON number; and

[0033] Figure 3 is a flowchart of an exemplary method for determining the ignition angle for the operation of an internal combustion engine.

[0034] As stated at the outset, this document deals with increasing the efficiency of an internal combustion engine when operating with a fuel having a particularly high RON number (e.g., RON>100). In this context, Fig. 1a shows an exemplary vehicle 100 with an internal combustion engine 102 that is configured to drive the vehicle 100 and that is powered by a fuel (e.g., gasoline). A (control) device 101 of the vehicle 100 can be configured to determine the ignition angle for operating the internal combustion engine 102. It should be noted that the terms ignition angle and ignition timing are used interchangeably in this document.

[0035] The vehicle 100 comprises one or more sensors 104 that are configured to determine one or more operating conditions for the operation of the internal combustion engine 102 (i.e., the operating point of the internal combustion engine 102), such as the load and / or the speed of the internal combustion engine 102. Furthermore, the vehicle 100 can comprise one or more sensors 103 that are configured to detect one or more actual boundary conditions for the operation of the internal combustion engine 102, such as the temperature (e.g., of the fuel, the intake air, the coolant, and / or the immediate surroundings of the combustion chamber). The device 101 can be configured to determine the ignition angle for the operation of the internal combustion engine 102 as a function of the operating point of the internal combustion engine 102 and / or as a function of the one or more actual boundary conditions.

[0036] Fig. 1b shows an exemplary ignition angle map 110 that was determined prior to the operation of the internal combustion engine 102 (e.g., experimentally and / or based on a simulation). The ignition angle map 110 specifies a standard ignition angle 113 for a combination of one or more operating parameters (e.g., the load 112 and / or the rotational speed 111) of the internal combustion engine 102 (i.e., for an operating point of the internal combustion engine 102). The ignition angle map 110 may have been determined for a fuel having a standard RON value. Furthermore, the ignition angle map 110 may have been determined for one or more standard boundary conditions. The standard ignition angle 113 can be the earliest possible ignition angle when using a fuel with the standard RON value and when one or more standard boundary conditions are present, so that an efficiency-optimized operation of the internal combustion engine 102 is achieved.

[0037] If the fuel used during operation has the standard RON value and if the one or more standard boundary conditions are present, then the internal combustion engine 102 can be operated with the standard ignition angle 113. If, on the other hand, the actual RON value deviates from the standard RON value and / or the one or more actual boundary conditions deviate from the one or more corresponding standard boundary conditions, an adjustment of the standard ignition angle 113 is typically required in order to continue to effect efficiency-optimized operation of the internal combustion engine 102. Fig. 1c illustrates an example adjustment of the standard ignition angle 113. Using a correction unit 120, an offset value 122 can be determined, with which the standard ignition angle 113 can be adjusted, in particular adjusted (retarded), in order to determine the operating ignition angle 123 for the operation of the internal combustion engine 102.The (model-based) correction unit 120 can be configured to determine the offset value 122 based on the one or more actual boundary conditions 121 (in particular based on the actual temperature (e.g., of the fuel, the intake air, the coolant, and / or the immediate surroundings of the combustion chamber)) and / or based on the actual RON value. The adjustment of the standard ignition angle 113 described in connection with Fig. 1c is based on the assumption that the actual RON value of the fuel is always smaller than the standard RON value (i.e., the design RON value).

[0038] The development of new fuels is leading to the availability of fuels with a particularly high RON value (e.g., RON>100). As a result, the standard or design RON value increases, for which an ignition angle map 110 must be determined and stored in the vehicle 100. As explained above, the internal combustion engine 102 typically has one or more limit values ​​that should not be exceeded during operation of the internal combustion engine 102, e.g., a pressure limit value, for example, for the piston, for the connecting rod bearing, for the spark plug, etc., and / or a temperature limit value, for example, for the piston, for the connecting rod bearing, for the spark plug, etc.This in turn has the consequence that when using a fuel with a relatively high standard RON value and when one or more standard boundary conditions are present, an efficiency-optimized standard ignition angle 113 cannot be determined (which lies at the knock limit of the internal combustion engine 102) for at least some of the possible operating points. For these operating points, a standard ignition angle 113 is then typically stored in the characteristic map 110, which results from the one or more limit values ​​of the internal combustion engine 102. If the internal combustion engine 102 is operated with a fuel which has an actual temperature which deviates from the standard temperature, in particular which is higher than the standard temperature, the correction unit 120 determines an offset value 122, by means of which the standard ignition angle 113 is increased from the ignition angle characteristic map 110, i.e. adjusted in the "retard" direction. Such a correction of the standard ignition angle 113 may be necessary.not required if the standard ignition angle 113 indicated by the characteristic map 110 is not at the head limit due to the relatively high standard RON value. As a result, the internal combustion engine 102 is not operated in an efficiency-optimized manner at an actual boundary condition 121 (in particular at an actual temperature (e.g., of the fuel, the intake air, the coolant, and / or the immediate surroundings of the combustion chamber)) that deviates from the corresponding standard boundary condition.

[0039] Fig. 2 shows an exemplary device 200 that enables efficiency-optimized operation of the internal combustion engine 102, even based on an ignition angle characteristic map 110 for a fuel with a particularly high standard RON value. For this purpose, the device 200 comprises a compensation unit configured to determine a knock limit distance 222 for each of the different operating points (in particular for different combinations of load 112 and speed 111) of the internal combustion engine 102. The compensation unit can be based on a previously determined compensation or knock limit map 220, which specifies the knock limit distance 222 for each of the different operating points.

[0040] The knock limit distance 222 for an operating point can depend on how far the standard ignition angle 113 displayed by the ignition angle map 110 (due to one or more limit values ​​of the internal combustion engine 102) deviates from the knock limit (and thus from efficiency-optimized operation of the internal combustion engine 102). The knock limit distance 222 can be different for different operating points (and possibly for different operating modes of the internal combustion engine 102). The compensation map 220 for determining the respective knock limit distance 222 can have been determined prior to the operation of the internal combustion engine 102 (experimental and / or based on simulation).

[0041] Thus, based on the one or more actual boundary conditions 121, an offset value 122 can be determined for the standard ignition angle 113 indicated by the ignition angle map 110 (for the current operating point). Furthermore, the knock limit distance 222 for the current operating point of the internal combustion engine 102 can be determined (if necessary, taking into account the one or more actual boundary conditions 121). The standard ignition angle 113 can then be adjusted based on the offset value 122 and based on the knock limit distance 222 in order to determine the operating ignition angle 123 for the operation (in particular for the pre-control) of the internal combustion engine 102. For example, the operating ignition angle 113 ZB can be determined as ZB = ZN + O - K, where ZN is the standard ignition angle 113, where O is the offset value 122, and where K is the knock limit distance 222.

[0042] As stated above, an internal combustion engine 102 should be operated at the knock limit with optimal efficiency across the entire operating range (i.e., for all operating points). The knock resistance of fuels (i.e., the RON value of fuels) continues to increase due to technical improvements in production. The measures described in this document make it possible to utilize the efficiency-related potential offered by these fuels with regard to knock resistance in an efficient and reliable manner.

[0043] Through a control and / or regulation method during operation of the internal combustion engine 102, the quality, i.e., the actual RON value, of the fuel currently being used can be determined based on a measurement of the knock limit (which is detected via knock detection and regulation). Using this determined fuel quality, the ignition pre-control (i.e., the operating ignition angle 123) can be appropriately corrected. Furthermore, a model can be used to correct the ignition pre-control (i.e., to determine the operating ignition angle 123), which takes into account the intake temperature (i.e., the actual temperature) and / or the engine temperature.

[0044] If the ignition cannot be selected as early as possible for the fuel without restriction across the entire map range (e.g., because otherwise the component temperature limit of the spark plug would be exceeded), the measured knock limit is typically no longer meaningful with regard to the quality (especially with regard to the actual RON value) of the fuel used. These operating ranges of the internal combustion engine 102 therefore cannot be taken into account when determining the fuel quality, so that a determination of the fuel quality in these ranges is not possible.

[0045] As already explained, when using very knock-resistant fuels (RON values ​​> 100) in the high-load range, the knock limit may no longer be measurable, since under conditions favorable for the knock tendency (low ambient and engine temperatures), particularly under one or more standard boundary conditions, otherwise maximum permissible pressures in the combustion chamber (i.e. limit values ​​of the internal combustion engine 102) are exceeded. These maximum permissible pressures are defined, for example, by the component strength limits of the components involved in combustion (e.g. components of the piston assembly and / or the spark plug and / or the connecting rod bearing, etc.) as well as components of the valve and crank train. Due to the required distance from the knock limit, general application and / or error-free function of the fuel quality detection described above is therefore no longer possible. Under knock-critical actual boundary conditions due to elevated temperatures (e.g.of the fuel, the intake air and / or the engine 102), the ignition is typically corrected towards late (by the correction unit 120). If, when using a fuel with a relatively high octane number, the same retardation of the ignition angle is used at operating points in which (given the existence of one or more standard boundary conditions) a knock limit margin exists to comply with the maximum permissible pressures (i.e., the one or more limit values ​​of the internal combustion engine 102), the fuel efficiency potential is not utilized. This typically increases the consumption and / or CO2 emissions and / or exhaust gas temperatures of the internal combustion engine 102, even though this would not be necessary under actual boundary conditions that deviate from the standard boundary conditions.

[0046] As explained above, the knock path adaptation can transmit an offset 122 appropriate for the currently used fuel quality to the ignition pre-control. This offset 122 can also be corrected by the knock limit 222 (e.g., in the form of a value read from a speed / load-dependent characteristic map 220). This allows fuel quality to be determined, or the fuel quality to be consistently calculated, even in operating ranges where the knock limit cannot be reached with all fuels (e.g., due to maximum permissible pressure limits in the combustion chamber).

[0047] Alternatively or additionally, the correction of the ignition pre-control (e.g., a correction due to a deviation from a standard boundary condition, such as a standard temperature) can be offset against the knock limit 222 to determine the operating ignition angle 123. This can only be effected if a specific activation condition is met. An example activation condition is that, based on the knock path adaptation, it is detected that the actual RON value of the fuel reaches or exceeds a specific RON threshold (whereby the RON threshold can be different for different operating points of the combustion engine 102). By taking the knock limit 222 into account, the RON potential of a high-octane fuel can be fully utilized to minimize CO2 and / or fuel consumption, and / or negative effects from degradation measures can be minimized.

[0048] Fig. 3 shows a flowchart of a (possibly computer-implemented) method 300 for operating an internal combustion engine 102 with a fuel, wherein the fuel has an actual RON value. The method 300 can be designed, in particular, to determine the operating ignition angle 123 for the operation (in particular for the pre-control of the ignition angle control) of the internal combustion engine 102.

[0049] The method 300 includes determining 301, based on (previously determined) ignition angle characteristic data 110, a standard ignition angle 113 for the (currently present) actual operating point of the internal combustion engine 102. The ignition angle characteristic data 110 can each specify a standard ignition angle 113 for a plurality of different possible operating points. A possible operating point can possibly correspond to a combination of load 112 and speed 111 of the internal combustion engine 102. The ignition angle characteristic data 110 can have been determined for a fuel having a standard RON value. Furthermore, the ignition angle characteristic data 110 for the operation of the internal combustion engine 102 can be determined when one or more standard boundary conditions are present (e.g. when a standard temperature of the fuel and / or the intake air is present, when a standard temperature of the internal combustion engine is present and / or when a standard lambda value is present (iea standard ratio of combustion air and fuel). During the current operation of the internal combustion engine 102, one or more actual boundary conditions may exist that deviate from the one or more corresponding standard boundary conditions.

[0050] The method 300 further includes determining 302, based on knock limit distance characteristic data 220 and for the actual operating point of the internal combustion engine 102, a knock limit distance 222 of the standard ignition angle 113 from the knock limit of the internal combustion engine 102. The knock limit distance 222 can indicate the ignition angle delta by which the standard ignition angle 113 deviates from the knock limit of the internal combustion engine 102 at the (current) actual operating point (and when the one or more actual boundary conditions are present). The knock limit distance 222 can depend on the one or more actual boundary conditions, in particular on the deviation of the one or more actual boundary conditions from the one or more corresponding standard boundary conditions.

[0051] Furthermore, the method 300 comprises determining 303 an operating ignition angle 123 for the operation of the internal combustion engine 102 and / or the actual RON value of the fuel on the basis of the standard ignition angle 113 and on the basis of the knock limit distance 222.

[0052] The measures described in this document make it possible to achieve efficiency-optimized operation of the internal combustion engine 102 in an efficient and reliable manner, even with fuels having a particularly high RON value.

[0053] The present invention is not limited to the embodiments shown. In particular, it should be noted that the description and figures are intended only to illustrate the principle of the proposed methods, devices, and systems by way of example.

Claims

Claims 1) Device (101) for operating an internal combustion engine (102) with a fuel; wherein the device (101) is arranged - to determine a standard ignition angle (113) for an actual operating point of the internal combustion engine (102) on the basis of ignition angle characteristic data (110); - to determine a knock limit distance (222) of the standard ignition angle (113) from a knock limit of the internal combustion engine (102) based on knock limit distance characteristic data (220) for the actual operating point of the internal combustion engine (102); and - to determine an operating ignition angle (123) for the operation of the internal combustion engine (102) and / or an actual RON value of the fuel on the basis of the standard ignition angle (113) and on the basis of the knock limit distance (222). 2) Device (101) according to claim 1, wherein the ignition angle characteristic data (110) are based on one or more standard boundary conditions for the operation of the internal combustion engine (102); and wherein the device (101) is arranged, - to determine one or more actual boundary conditions for the operation of the internal combustion engine (102); wherein the one or more actual boundary conditions deviate at least partially from the one or more corresponding standard boundary conditions; - to determine an offset value (122) using a correction unit (120), in particular a model-based one, and on the basis of the one or more actual boundary conditions; and - to determine the operating ignition angle (123) for the operation of the internal combustion engine (102) and / or the actual RON value of the fuel also on the basis of the offset value (122). ) Device (101) according to one of the preceding claims, wherein the device (101) is arranged - to determine an adaptation ignition angle delta of the standard ignition angle (113) from the knock limit of the internal combustion engine (102) based on a knock path adaptation, in particular when one or more actual boundary conditions are present; and - to determine the operating ignition angle (123) for the operation of the internal combustion engine (102) and / or the actual RON value of the fuel also on the basis of the adaptation ignition angle delta. ) Device (101) according to claim 3, wherein - the ignition angle characteristics (110) are based on operation of the internal combustion engine (102) with fuel having a standard RON value; and - the device (101) is configured to reduce the standard RON value by a first delta RON value dependent on the adaptation ignition angle delta and to increase a second delta RON value dependent on the knock limit distance (222) in order to determine the actual RON value of the fuel with which the internal combustion engine (102) is operated. ) Device (101) according to one of the preceding claims, wherein the device (101) is configured, - to determine the actual RON value of the fuel with which the internal combustion engine (102) is operated; - to compare the actual RON value with a RON threshold value; and - depending on the comparison, to take into account or not to take into account the knock limit distance (222) when determining the operating ignition angle (123). ) Device (101) according to claim 5, wherein the device (101) is configured to take the knock limit distance (222) into account when determining the operating ignition angle (123), in particular to take it into account only when the actual RON value is equal to or greater than the RON threshold value. ) Device (101) according to one of the preceding claims, wherein - the ignition angle characteristics (110) are based on one or more standard boundary conditions for the operation of the internal combustion engine (102); - which include one or more standard boundary conditions in particular, - a standard temperature of the fuel; - a standard temperature of the air sucked in by the internal combustion engine (102); - a standard temperature of coolant for cooling the internal combustion engine (102); and / or - a standard temperature of the combustion engine (102); and / or - a standard lambda value; - the ignition angle characteristics (110) are based on operation of the internal combustion engine (102) with fuel having a standard RON value; - the ignition angle characteristic data (110) were determined with the aim of providing a standard ignition angle (113) for a plurality of possible operating points of the internal combustion engine (102), which lies at the knock limit of the internal combustion engine (102) when the one or more standard boundary conditions are present; and - the standard RON value is so high that, due to one or more physical limit values ​​of the internal combustion engine (102), the ignition angle characteristic data (110) for at least some of the plurality of possible operating points each indicate a standard ignition angle (113) which has an ignition angle delta from the knock limit of the internal combustion engine (102) when the one or more standard boundary conditions are present. ) Device (101) according to one of the preceding claims, wherein the device (101) is configured, - to determine one or more actual boundary conditions for the operation of the internal combustion engine (102); wherein the one or more actual boundary conditions deviate at least partially from the one or more corresponding standard boundary conditions; - to determine the knock limit distance (222) of the standard ignition angle (113) from the knock limit of the internal combustion engine (102) as a function of the one or more actual boundary conditions, in particular as a function of a deviation of the one or more actual boundary conditions from the one or more corresponding standard boundary conditions. ) Device (101) according to one of the preceding claims, wherein the ignition angle characteristic data (110) and / or the knock limit distance characteristic data (220) have been determined experimentally and / or based on simulations prior to the operation of the internal combustion engine (102). 0) Method (300) for operating an internal combustion engine (102) with a fuel; wherein the method (300) comprises, - determining (301), on the basis of ignition angle characteristic data (110), a standard ignition angle (113) for an actual operating point of the internal combustion engine (102); - Determining (302), based on knock limit distance characteristic data (220) and for the actual operating point of the internal combustion engine (102), a knock limit distance (222) of the standard ignition angle (113) from a knock limit of the internal combustion engine (102); and - Determining (303) an operating ignition angle (123) for the operation of the internal combustion engine (102) and / or an actual RON value of the fuel based on the standard ignition angle (113) and on the basis of the knock limit distance (222).

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