Method for determining the ignition angle efficiency and ignition angles in an internal combustion engine having a plurality of spark plugs per cylinder

Abstract

A computer-implemented method for determining the ignition angle efficiency and / or preferably an engine torque for controlling an engine having n spark plugs per cylinder (n≥2) has the following steps: calculating (S1) n optimum ignition angles for n spark plugs of the engine on the basis of speed information and load information of the engine; calculating (S2) n ignition angle differences on the basis of the respective optimum ignition angle and the respective actual ignition angle of the respective spark plug; calculating (S3), on the basis of the ignition angle differences, an n-dimensional hyperplane on which each (n+1) dimensional point indicates an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs; preferably determining (S4) an engine torque model and / or an engine torque hyperplane on the basis of the hyperplane; determining (S5) a determined ignition angle efficiency and / or preferably a determined engine torque on the basis of the calculated hyperplane and / or the determined engine torque model and / or the determined engine torque hyperplane as a function of a determined combination of ignition angle differences of the n spark plugs; and controlling (S6) the engine on the basis of the determined ignition angle efficiency and / or preferably the determined engine torque.

Description

[0001] Description

[0002] title

[0003] METHOD FOR DETERMINING IGNITION ANGLE EFFICIENCY AND IGNITION ANGLES IN AN INTERNAL ENGINE WITH MULTIPLE SPARK PLUGS PER CYLINDER

[0004] The invention relates to a computer-implemented method and a device for determining an ignition angle efficiency and / or, in particular, an engine torque dependent thereon for controlling an engine. The invention further relates to a computer-implemented method and a device for determining a combination of ignition angles of n spark plugs, in particular for adjusting n ignition timings in an engine.

[0005] State of the art

[0006] In modern automotive engineering, the optimization of internal combustion engines plays a crucial role in increasing performance and efficiency while reducing emissions. A key element in this endeavor is the precise control of the ignition timing in gasoline engines, where one or more spark plugs per cylinder play a vital role. The use of multiple spark plugs (CC1, CC2, CC3) per cylinder 1 in a combustion chamber, as illustrated in Fig. 1, enables improved combustion through a more even distribution of the ignition energy within the combustion chamber. The ignition of individual spark plugs is not controlled; instead, the spark plugs are activated simultaneously or with a time offset.

[0007] Adjusting the ignition timing, also called ignition angle, is based on a variety of factors, including engine speed and cylinder filling, i.e., the amount of air entering the combustion chamber. By being able to vary the ignition timing within physical limits, engine efficiency can be maximized. Ignition efficiency is measured as the deviation from an ideal ignition timing, at which efficiency theoretically reaches a value of 1.0, as illustrated in Fig. 2 (prior art) under the term ETADZW.

[0008] The optimal ignition timing and the associated engine torque are determined through precise measurements under various operating conditions on an engine test bench. The resulting engine torque model, visualized in Fig. 4 (state of the art), represents the theoretically maximum torque achievable under specific operating conditions. The integration of this model, along with the ignition timing efficiency as a 2D characteristic curve (Fig. 2 (state of the art): ETADZW) and the corresponding inverse 2D characteristic curve (Fig. 3 (state of the art): DZWETA), into the engine control software represents the state of the art in gasoline engine optimization.

[0009] These technological advances make it possible to further improve the performance and efficiency of gasoline engines by allowing for more precise adjustment of the ignition timing to the respective operating conditions. This not only leads to optimized fuel consumption and reduced emissions, but also contributes to an enhanced driving experience through improved engine performance.

[0010] Although approaches to more precisely adapting the ignition timing to the respective operating conditions in order to optimize fuel consumption, reduce emissions and increase the driving experience through improved engine performance are already known from the state of the art, there is still potential for development.

[0011] It is an object of the invention to provide a method and / or a device improved in this respect.

[0012] The problem is solved by a method according to the features of claim 1 and claim 3. The problem is solved by a device according to the features of claim 14 and claim 15. Disclosure of the invention

[0013] According to a first aspect, a computer-implemented method for determining an ignition angle efficiency and / or, in particular, an engine torque dependent thereon for controlling an engine, where n > 2, the method comprising the steps:

[0014] Calculating n optimal ignition angles for n spark plugs based on speed and load information of the engine;

[0015] Calculating n ignition angle differences based on the respective optimal ignition angle and a respective actual ignition angle of the respective spark plug;

[0016] Calculating an n-dimensional hyperplane in an (n+1)-dimensional space, on which each (n+1)-dimensional point specifies an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs, based on the ignition angle differences; preferably determining an engine torque model and / or an engine torque hyperplane based on the hyperplane;

[0017] Determining a specific ignition timing efficiency and / or preferably a specific engine torque based on the provided hyperplane and / or preferably the engine torque model and / or the engine torque hyperplane as a function of a specific combination of ignition timings of the n spark plugs; and

[0018] Controlling the engine based on the specified ignition timing efficiency and / or preferably the specified engine torque

[0019] Particularly preferably, the method further features motor control based on the provided hyperplane and / or the motor torque model and / or the motor torque hyperplane. The speed information can, for example, be the motor speed.

[0020] The present method, according to the first aspect, preferably enables the creation of an engine torque model for engines with at least two, or up to n, spark plugs, where n is a real number greater than or equal to n. The method is thus designed for engines in which the combustion process is characterized by at least two independently controllable ignitions of spark plugs. To create the engine torque, or an engine torque model for two ignitions, an extension from two dimensions to at least three dimensions, and possibly up to an n-dimensional space, is necessary compared to known approaches. This is achieved here by calculating the hyperplane.

[0021] According to a second aspect, a computer-implemented method for determining a combination of ignition angles of n spark plugs, in particular for adjusting n ignition timings in an engine, is proposed; where n > 2, the method comprising the steps:

[0022] Providing an n-dimensional hyperplane in an (n+1)-dimensional space, on which each (n+1)-dimensional point specifies an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs; wherein, on the hyperplane, for each ignition angle efficiency, a plurality of possible combinations of ignition angle differences of the n spark plugs exist on a respective iso-function;

[0023] Defining a boundary condition that restricts and thus makes determinable the multitude of possible combinations of ignition angle differences of the n spark plugs on an iso-function;

[0024] Determining a combination of ignition angle differences of the n spark plugs based on a predetermined ignition angle efficiency, based on the boundary condition and the iso-function dependent on the predetermined ignition angle efficiency; and

[0025] Controlling the engine based on the specific combination of ignition angles of the n spark plugs.

[0026] Defining a boundary condition refers to specifying particular conditions and / or constraints. Defining a boundary condition limits the number of possible ignition timing differential combinations for the spark plugs. Factors influencing the boundary condition could include, for example, a specific engine load, speed range, and / or temperature. The iso function in this context is a mathematical representation that maps all possible combinations of ignition timing differentials that result in a consistent ignition timing efficiency. Once the boundary condition has been defined, a specific combination of ignition timing differentials is selected for the spark plugs. This selection is based on the previously defined ignition timing efficiency, which may relate to the engine's optimal performance or fuel consumption.The "iso-function dependent on predetermined ignition timing efficiency" refers to a curve or surface representing all combinations of ignition timing differences that achieve this specific efficiency. The selection is made to best meet the desired efficiency criteria under the given boundary conditions. In the final step, the engine is controlled based on the determined combination of ignition timings. This means that the engine control unit adjusts the ignition timing of each cylinder accordingly to achieve the previously determined optimal efficiency and power output. This adjustment occurs in real time and can adapt to changing operating conditions such as load changes, engine speed variations, or differing environmental conditions.

[0027] The inverse of a two- or n-dimensional function is mathematically underdetermined and thus leads to infinitely many solutions. All solutions lie on an isoline (in three-dimensional space) or an isofunction (in n-dimensional space) on which all points exhibit the same ignition angle efficiency. To arrive at a uniquely determinable solution, an additional boundary condition or strategy is required. Such a boundary condition or strategy can be the definition of a strategy curve on the n-dimensional hyperplane, on which the ignition angle efficiency preferably exhibits monotonic behavior, such that the strategy curve preferably intersects the isofunction only once. The point of intersection corresponds to the now unique solution of the inverse function for the predetermined combination of ignition angle differences.

[0028] This process is also known as "ignition timing retard." Ignition timing retard, also referred to as ignition timing adjustment, involves retarding the ignition timing of an engine towards later stages in the combustion cycle. This ignition timing retard can be used to prevent engine knocking and / or to allow for rapid torque intervention (e.g., via an idle air control valve, transmission intervention, or traction control, etc.). Engine knocking or uncontrolled combustion can occur when the fuel-air mixture is ignited too early, resulting in uneven and explosive combustion.

[0029] Retarding the ignition timing reduces the risk of knocking because combustion occurs under less extreme pressure conditions. Earlier ignition increases efficiency and lowers engine temperature but increases the tendency for knocking. Retarder decreases efficiency and the tendency for knocking but increases engine temperature. Furthermore, different fuel types and qualities have different combustion characteristics. With lower octane fuels, which are more prone to knocking, ignition timing retardation may be necessary to optimize engine operation. Additionally, under certain load conditions, particularly at low loads and high engine speeds, ignition timing retardation can help improve efficiency and avoid unnecessary mechanical stress on the engine. Adjusting the ignition timing can also affect emissions.A later ignition timing can help reduce NOx (nitrogen oxide) emissions by lowering combustion temperatures.

[0030] According to a third aspect, it is proposed to use a device, in particular a control unit, preferably an engine control unit, for determining an ignition angle efficiency and / or preferably an engine torque dependent thereon for controlling an engine, wherein n > 2, wherein the device is configured to perform the following steps:

[0031] Calculating n optimal ignition angles for n spark plugs based on speed and load information of the engine;

[0032] Calculating n ignition angle differences based on the respective optimal ignition angle and a respective actual ignition angle of the respective spark plug; calculating an n-dimensional hyperplane in an (n+1)-dimensional space, on which each (n+1)-dimensional point specifies an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs, based on the ignition angle differences; preferably determining an engine torque model and / or an engine torque hyperplane based on the hyperplane;

[0033] Determining a specific ignition timing efficiency and / or preferably a specific engine torque based on the provided hyperplane and / or preferably the engine torque model and / or the engine torque hyperplane as a function of a specific combination of ignition timing differences of the n spark plugs; and

[0034] Controlling the engine based on the specified ignition timing efficiency and / or preferably the specified engine torque

[0035] According to a fourth aspect, it is proposed to provide a device, in particular a control unit, preferably an engine control unit, for determining a combination of ignition angles of n spark plugs, in particular for adjusting n ignition timings in an engine; wherein n > 2, the device being configured to perform the following steps:

[0036] Providing an n-dimensional hyperplane in an (n+1)-dimensional space, on which each (n+1)-dimensional point specifies an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs; wherein, on the hyperplane, for each ignition angle efficiency, a plurality of possible combinations of ignition angle differences of the n spark plugs exist on a respective iso-function;

[0037] Defining a boundary condition that restricts and thus makes determinable the multitude of possible combinations of ignition angle differences of the n spark plugs on an iso-function;

[0038] Determining a combination of ignition angle differences of the n spark plugs based on a predetermined ignition angle efficiency, based on the boundary condition and the iso-function dependent on the predetermined ignition angle efficiency; and

[0039] Controlling the engine based on a specific combination of ignition timings. It is understood that the steps according to the invention, as well as further optional steps, do not necessarily have to be carried out in the sequence shown, but can also be carried out in a different sequence. Furthermore, additional intermediate steps may be provided. The individual steps may also comprise one or more sub-steps without thereby departing from the scope of the method according to the invention.

[0040] The statements made regarding the procedure apply accordingly to the device. It is understood that linguistic modifications of procedurally formulated features can be reformulated for the device according to common linguistic practice, without such formulations needing to be explicitly listed here.

[0041] The term "hyperplane" refers to a generalization of a plane in higher-dimensional spaces. Formally, a hyperplane in an n-dimensional space is an (n-1) dimensional subspace. This means that in a three-dimensional space (such as the space surrounding us), a hyperplane is an ordinary two-dimensional plane. In a four-dimensional space, a hyperplane is a three-dimensional subspace. Geometrically, a hyperplane divides space into two halves.

[0042] "Ignition timing efficiency" refers to the relationship between the achieved engine power or efficiency and the ignition timing setting. High ignition timing efficiency means that the engine produces more power with lower fuel consumption at a given ignition timing.

[0043] Engine torque is the force that the engine generates to propel a vehicle. It is measured in Newton meters (Nm) and indicates how strongly the engine is able to turn the axle to which the wheels are attached.

[0044] The "optimal ignition timing" is the ignition point at which the engine achieves its maximum efficiency or power output. This timing is set to ensure optimal combustion of the fuel-air mixture in the cylinder, maximizing the expansion of the combustion gases at the ideal point during the engine's power stroke. "Speed ​​information" refers to data concerning a vehicle's speed or engine speed. This information can be used for various control functions within the vehicle, including adjusting the ignition timing or fuel supply.

[0045] The "load information" refers to the current load or demand on the engine, such as during acceleration, uphill driving, or towing a trailer. This information is important for the engine control unit to adjust the fuel supply, ignition timing, and other parameters accordingly. The load information is preferably measured in the engine control unit using cylinder filling (air).

[0046] An "engine torque model" is a mathematical model that predicts the behavior or output of engine torque under various operating conditions. It can take into account various variables, such as engine load, speed, temperature, and ignition timing. The engine torque model can incorporate thermodynamic calculations, empirical data, and / or simulations of combustion dynamics.

[0047] The "engine torque hyperplane" is a concept from control engineering that represents a multidimensional surface or plane on which the relationship between engine torque and various influencing factors such as ignition angle, load and speed is visualized.

[0048] A "combination of ignition timings" refers to the specific setting or sequence of ignition points in a multi-cylinder engine. Different combinations can be tested to achieve optimal engine performance and efficiency under various operating conditions.

[0049] The conversion of ignition timing efficiency to engine torque is preferably not done directly, but through a complex process involving several steps and calculations. Ignition timing efficiency influences the torque produced. It affects how completely the fuel is burned in the combustion chamber. An optimal ignition timing ensures efficient combustion, converting more of the chemical energy stored in the fuel into usable mechanical energy. Efficient combustion increases the pressure curve in the cylinder during combustion. This pressure acts on the piston and generates a force that is converted into torque by the crankshaft mechanism. The shape and peak of the pressure curve are crucial for the amount of torque produced.Engine torque can then be calculated taking into account cylinder pressure, piston diameter, connecting rod length, crankshaft geometry, and other factors. Ignition timing efficiency indirectly influences torque through its effect on the combustion process and pressure curve. An optimized ignition timing leads to an improved pressure curve, which increases the maximum torque at a given engine speed. In practice, a detailed engine torque model, which considers many variables to calculate torque based on ignition timing efficiency and other factors, is preferred.

[0050] It is important to note that directly converting ignition timing efficiency to engine torque is complex and requires a precise analysis of the specific engine and its operating conditions. The steps above provide a general overview of the process, but the specific calculations may vary depending on the engine type and application.

[0051] This document provides a software solution that enables the individual control of the ignition timing for at least two spark plugs in an internal combustion engine. This allows for influencing the combustion behavior and optimizing it for a specific operating point. Different combustion behaviors can arise, for example, from different geometric arrangements of the spark plugs in the combustion chamber or from different designs. These designs can include: conventional spark plugs, pre-chamber spark plugs (i.e., spark plugs with an integrated pre-chamber cap), or conventional spark plugs in a separate pre-chamber. To implement and utilize individual ignition timing for two or more spark plugs, it is advantageous to also calculate the ignition angle efficiency inversely. This corresponds to calculating the resulting engine torque from a set ignition angle and vice versa.the ignition timing to be set for a desired engine torque.

[0052] The method enables a more precise and situation-adapted determination of the engine torque for internal combustion engines with two ignitions by providing a systematic method to overcome the challenges associated with the mathematical underdetermination of the inverse function and the need for a unique solution for the combination of ignition angles.

[0053] In another aspect, it is proposed that determining the combination of ignition angles involves a calculation based on n optimal ignition angles of the n spark plugs and the respective actual ignition angles of the n spark plugs.

[0054] Determining the ignition timing combination preferably involves selecting a combination of ignition timings for all spark plugs in an engine. The "ignition timing combination" describes how the ignitions are distributed across the different cylinders to achieve optimal combustion conditions. The selection can be based on a number of factors, including engine load, speed, and other operating conditions. An "optimal ignition timing" is preferably calculated for each spark plug in the engine. This optimal timing is the point at which the ignition of the fuel-air mixture in each cylinder provides the best combination of fuel efficiency, power output, and emission reduction. The number of optimal ignition timings corresponds to the number of spark plugs in the engine, hence "n optimal ignition timings" for "n spark plugs." In addition to calculating the optimal ignition timings, it is also preferred to consider the actual ignition timings.The "actual ignition angle" refers to the angle at which ignition occurs in practice. This can deviate from the calculated optimal angles due to various factors, such as wear, spark plug aging, or changes in the quality of the fuel-air mixture. Furthermore, it is proposed that the provision of the n-dimensional hyperplane involves: calculating n optimal ignition angles for n spark plugs based on speed and load information of the engine; calculating n ignition angle differences based on the respective optimal ignition angle and the respective actual ignition angle of each spark plug; and calculating the n-dimensional hyperplane based on the ignition angle differences.

[0055] This approach essentially corresponds to that of the first aspect. The first and second aspects are the addition of a (common) control strategy for the motor, whereby the second aspect draws on sub-aspects of the first aspect, but adds the boundary condition in order to achieve invertibility in particular.

[0056] In another aspect, it is proposed that the hyperplane be provided based on an engine torque model and / or an engine torque hyperplane.

[0057] Other parameters for creating the hyperplane and / or efficiency tests on an engine test bench can also be used to create the hyperplane.

[0058] In another aspect, it is proposed that by defining the boundary condition, especially in the form of an n-dimensional strategy function, the hyperplane can be inverted.

[0059] An n-dimensional strategy function is a mathematical function that operates in an n-dimensional space and assigns values ​​or strategies based on the position within that space. A boundary condition, in this context, defines restrictions or conditions for the strategy function. Establishing boundary conditions is crucial for determining the validity and applicability of the function in a given context. Boundary conditions can include limits, state conditions, or specific properties that the strategy function must satisfy. Invertibility, in this context, refers to the ability to reverse an operation or transformation represented by the hyperplane.If the hyperplane becomes invertible by defining an n-dimensional strategy function under certain boundary conditions, this means that the transformation represented by this hyperplane is reversible. This implies that for every assignment or decision made by the hyperplane and the strategy function, a unique inverse exists that allows us to deduce the original state from the result.

[0060] In another aspect, it is proposed that the boundary condition be chosen based on the engine and / or the combustion quality of an engine ignition at a specific operating point, in order to achieve optimal engine torque and / or efficiency values ​​in particular.

[0061] Other influencing factors are also possible, so the list should not be understood as limiting.

[0062] In another aspect, it is proposed that the boundary condition be chosen such that the boundary condition defines a strategy function with mathematically monotonic behavior that intersects the iso-function at a single intersection point.

[0063] The boundary condition is preferably a fixed parameter or a set of parameters that define the conditions or constraints. The strategy function is a mathematical function that describes a specific strategy or behavior within the defined boundary conditions. "Mathematically monotonic behavior" means that the function either increases or decreases continuously. This ensures a predictable and unambiguous relationship between the inputs (such as ignition timing) and the outputs (such as engine power or efficiency). The isofunction is a curve or surface representing all points at which a specific power or efficiency level is achieved.Defining the boundary condition and the strategy function in such a way that the iso-function is intersected at only a single point means that there is a unique solution or outcome for optimal performance under the given conditions.

[0064] In another aspect, it is proposed that the ignition angle efficiency of the n spark plugs varies based on a respective geometric arrangement of the n spark plugs and / or a type of the n spark plugs and / or an influence of the n spark plugs within a cylinder of the engine.

[0065] The positioning of the spark plugs in the cylinder plays a role in combustion efficiency. An optimal arrangement ensures that the fuel-air mixture burns evenly, resulting in more complete combustion and thus higher efficiency. The geometric arrangement primarily refers to the distance between the spark plugs, their placement relative to the cylinder wall and piston, and their orientation within the combustion chamber. The technology and design of the spark plugs themselves also influence ignition timing efficiency. Different spark plug types, such as those with multiple electrodes, platinum tips, or iridium tips, can exhibit different ignition characteristics. These characteristics include ignition temperature, lifespan, and the ability to produce a clean spark pattern.The influence of spark plugs refers to how their presence and function alter the combustion dynamics within a cylinder. Ignition efficiency can be affected by factors such as electrode gap, ignition voltage, and the heat dissipation of the spark plugs.

[0066] In a further aspect, it is proposed that the provision of the boundary condition be carried out taking into account a geometric arrangement of the n spark plugs, distinguishing between symmetrical systems, in which the n spark plugs are installed geometrically symmetrically and the influence of the respective ignition angle is symmetrical for n ignitions, and asymmetrical systems, in which the n spark plugs are installed geometrically asymmetrically, which leads in particular to an asymmetrical influence on the ignition angle efficiency. In a symmetrical system (e.g., two spark plugs installed geometrically symmetrically in the cylinder), the influence of the ignition angle on the ignitions is also symmetrical. In an asymmetrical system (e.g., two spark plugs installed geometrically asymmetrically in the cylinder), the influence of the ignition angle on the ignitions is also asymmetrical. A choice of the implemented orThe chosen boundary condition therefore depends on the system at hand and can, for example, also be influenced by the combustion quality of the respective ignition at the respective operating point.

[0067] In another aspect, a computer program with program code is claimed to execute at least parts of the present method in one of its aspects when the computer program is executed on a computer. In other words, a computer program (product) comprising instructions that, when executed by a computer, cause it to execute the method(s) in one of its aspects.

[0068] In a further aspect, a computer-readable data carrier containing the program code of a computer program is proposed to execute at least parts of the present method in one of its aspects when the computer program is executed on a computer. In other words, the invention relates to a computer-readable (storage) medium comprising instructions which, when executed by a computer, cause the computer to execute the method / steps of the method in one of its aspects.

[0069] The described configurations and training programs can be combined in any way desired.

[0070] Further possible embodiments, developments and implementations of the invention also include combinations of features of the invention described previously or subsequently with regard to the exemplary embodiments that are not explicitly mentioned.

[0071] Brief description of the drawings: The accompanying drawings are intended to provide a further understanding of the embodiments of the invention. They illustrate embodiments and, in conjunction with the description, serve to explain the principles and concepts of the invention.

[0072] Other embodiments and many of the aforementioned advantages become apparent with reference to the drawings. The elements depicted in the drawings are not necessarily shown to scale.

[0073] Fig. 1 shows a schematic representation of spark plugs for a

[0074] Cylinders according to the state of the art.

[0075] Fig. 2 shows a schematic representation of engine efficiency as a function of ignition angle deviation (ETADZW) according to the state of the art.

[0076] Fig. 3 shows a schematic representation of an inverse engine efficiency as a function of an ignition angle deviation (DZWETA) according to the prior art.

[0077] Fig. 4 shows a schematic visualization of an engine torque according to a prior art engine model.

[0078] Fig. 5 shows a schematic flowchart of one aspect of the present procedure;

[0079] Fig. 6 shows a schematic flowchart of one aspect of the present procedure;

[0080] Fig. 7 shows a schematic representation of ignition angle efficiencies for different combinations of ignition angles at a specific operating point of the engine.

[0081] Fig. 8 shows a schematic block diagram of a process. Fig. 9 shows a schematic 3-D representation of an engine efficiency KF as a function of ignition angle differences for an engine with two spark plugs per cylinder.

[0082] Fig. 10 shows a graphical illustration of an (iterative) calculation of the ignition angle differences suitable for the desired ignition efficiency of an engine with two spark plugs according to a strategy.

[0083] Fig. 11 shows a graphic illustration of the switching on and off of spark plugs.

[0084] In the figures of the drawings, identical reference symbols denote identical or functionally equivalent elements, parts or components, unless otherwise stated.

[0085] Figures 1 to 4 show schematic representations from the prior art, which were mentioned in the introductory part of the description. Figures 1 to 4 will not be mentioned again in the further course of the figure description.

[0086] Fig. 5 shows a schematic flowchart of a claimed method for determining an ignition angle efficiency and / or an engine torque for controlling an engine, wherein a number n of spark plugs is greater than or equal to (i.e., ">") two.

[0087] The computer-implemented procedure includes at least the following steps:

[0088] In step S1, n optimal ignition angles for n spark plugs are calculated based on engine speed and load information. In step S2, n ignition angle differences are calculated based on the respective optimal ignition angle and the respective actual ignition angle of each spark plug.

[0089] In step S3, an n-dimensional hyperplane is calculated in an (n+1)-dimensional space, on which each (n+1)-dimensional point specifies an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs, based on the ignition angle differences.

[0090] In step S4, preferably a motor torque model and / or a motor torque hyperplane is determined based on the hyperplane.

[0091] In step S5, a specific ignition angle efficiency and / or preferably a specific engine torque is determined based on the provided hyperplane and / or preferably the engine torque model and / or the engine torque hyperplane depending on a specific combination of ignition angle differences of the n spark plugs.

[0092] In step S6, the engine is controlled based on the determined ignition angle efficiency and / or preferably the determined engine torque.

[0093] Fig. 6 shows a schematic flowchart of a claimed method for determining a combination of ignition angles of n spark plugs, in particular for adjusting n ignition timings in an engine, wherein a number n of spark plugs is greater than or equal to (i.e., ">") two.

[0094] The computer-implemented procedure includes at least the following steps:

[0095] In step S11, an n-dimensional hyperplane is provided, on which each (n+1)-dimensional point represents an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs; where, on the hyperplane, for each ignition angle efficiency, a multitude of possible combinations of ignition angle differences of the n spark plugs exist on a respective isofunction. In step S12, a boundary condition is defined that restricts the multitude of possible combinations of ignition angle differences of the n spark plugs on an isofunction and thus makes them determinable.

[0096] In step S13, a combination of ignition angle differences of the n spark plugs is determined based on a predetermined ignition angle efficiency based on the boundary condition and the iso-function dependent on the predetermined ignition angle efficiency.

[0097] In step S14, the engine is controlled based on the specific combination of ignition angles of the n spark plugs.

[0098] The respective method can be carried out in any embodiment, at least partially, by a device 100, which may comprise several components not shown in detail, for example, one or more provisioning units and / or at least one evaluation and computing unit. It is understood that the provisioning unit may be designed together with the evaluation and computing unit, or it may be different from it. Furthermore, the device 100, which may be part of a system, may comprise a storage unit and / or an output unit and / or a display unit and / or an input unit.

[0099] Fig. 7 shows a diagram for the ignition timing efficiency for a specific operating point of the engine in a system with two spark plugs in different positions, namely laterally (iajat) and before top dead center (ia_pre). Fig. 7 shows the plotting of a characteristic map. The map shows various isolines with constant ignition timing efficiency; compare, for example, the isoline with reference numeral 700, where the ignition timing efficiency is 90% for a multitude of ignition timing combinations.

[0100] Fig. 8 shows a schematic block diagram of a method for determining an ignition angle efficiency 800. Here, the method is shown for two spark plugs (i.e., n=2). Two optimal ignition angles 802 (one for each spark plug) are calculated based on speed information 804 and load information 806 of the engine. For each spark plug, an ignition angle difference 808 is calculated based on the respective optimal ignition angle 802 and the respective actual ignition angle 810 of the respective spark plug. The calculation is performed by subtraction or a difference plot 812. The ignition angle differences 808 are fed into a function block 814 for calculating an n-dimensional hyperplane, on which each (n+1)-dimensional point indicates the ignition angle efficiency 800 for a combination of two ignition angle differences of the two spark plugs, based on the ignition angle differences 808.

[0101] Fig. 9 schematically shows the representation of such a hyperplane 900, here for two spark plugs, i.e., in 3-dimensional space. The hyperplane is a 2-dimensional plane. The ignition angle efficiency 800 is plotted as the abscissa over the ordinates of the respective ignition angle differences 908. The spark plugs are arranged in different positions, so that the ordinates are labeled dia_pre and diajat. For each ignition angle efficiency 800, there exists a multitude of possible combinations of ignition angle differences, which are arranged on a common isoline. To enable the invertibility of the function or the hyperplane, a boundary condition in the form of a strategy curve 902 is defined, which uniquely restricts and thus determines the multitude of possible combinations of ignition angle differences of the two spark plugs on the isoline.This allows a combination of ignition angle differences between the two spark plugs to be determined as the intersection of the isoline with the predetermined strategy curve for a specific ignition angle efficiency 800. Three strategy curves 902 are shown as examples in Fig. 9. With a symmetrical arrangement of the spark plugs, the strategy curve can also be chosen as an angle bisector or as a parallel offset to the angle bisector.

[0102] Fig. 10 shows a schematic representation of an ignition timing calculation for a software solution. The combination of ignition timing differences for the desired ignition timing efficiency is calculated along the fixed strategy curve 1002, which corresponds to the solution with the boundary condition. The ignition timing efficiency depends on the engine torque to be set. The corresponding combination of ignition timings is calculated iteratively in the engine control software until the desired engine torque is achieved. Here, strategy curve 1002 with a delta 1004 parallel to line 1000 is selected. The delta can be calibrated in various ways. Line 1000 corresponds to an angle bisector where ia_pre = iajat. An increase in the ignition timing differences, or a retardation of the ignition timing, can be considered along strategy curve 1002. The ignition timing efficiency then decreases monotonically along the strategy curve.

[0103] To enable a finite determination of the combination of ignition angles, a boundary condition or termination criterion is defined. The procedure for this can be described as follows:

[0104] An ignition angle efficiency (eta) is calculated step by step for the points [1 to x] until the ignition angle efficiency falls below an ignition angle efficiency eta_dem (Suggestion: Number the ISO line for eta_dem and reference it here. Example: "until the distance between the points x-1 and x intersects the ISO line eta_dem xxxx.").

[0105] The point spacing can vary depending on the gradient of the firing angle efficiency map (i.e., the hyperplane section), achieving better accuracy at high nonlinearity.

[0106] Furthermore, the combination of ignition angles of ia_pre and iajat is calculated via a linear interpolation between the points [x] and [x-1].

[0107] The ignition angle efficiency of the result point can be checked using the ignition angle efficiency eta_dem.

[0108] If a deviation exceeds a limit value, a new point between [x] and [x-1] can optionally be defined and calculated to obtain better accuracy for the ignition angle efficiency. This preferably corresponds to a bisection method.

[0109] Fig. 11 shows a diagram representing the switching on and off of individual spark plugs. To enable torque-neutral switching of one or more spark plugs, the ignition timing can be advanced (retarded) to a point where the spark plug being switched on or off no longer contributes to combustion efficiency. During this time, the change in ignition timing efficiency is compensated for by earlier ignition timing of the spark plug that remains active. Under certain conditions, it may be technically necessary or advantageous to switch off one or more spark plugs (e.g., combustion behavior or component protection), so that the engine operates with only one spark plug per cylinder. If the engine is subsequently switched to an operating state that requires the reactivation of one or more spark plugs, a logic that provides a torque-neutral switching operation is preferred for this process.

[0110] An example of such an implementation is shown in Fig. 11. A possible application can be described as follows. Switching off the ignition timing during ignition retardation up to a physical limit, beyond which further retardation is no longer possible without impairing combustion or damaging the engine, may be preferred. The range for ignition retardation can be extended if one or more spark plugs are switched back on. Thus, the ignition retardation limit can be extended beyond the isoline, creating a greater range for the overall ignition retardation. This is shown schematically in Fig. 11. The transition is preferably torque-neutral. Furthermore, hysteresis for the transition is preferred to prevent excessively frequent switching on and off.

[0111] A special case is knocking. When knocking is detected, the ignition timing is retarded, as in a conventional engine, to reduce the tendency to knock. If the engine is operating with only one spark plug engaged, the ignition timing retard may be limited. Engaging one or more spark plugs is then preferable to extend the range of maximum possible retardation.

Claims

Claims 1. Computer-implemented method for determining an ignition timing efficiency and / or preferably an engine torque for controlling an engine, wherein n > 2, the method comprising the steps: Calculating (S1) n optimal ignition angles of n spark plugs of the engine based on speed information and engine load information; Calculating (S2) n ignition angle differences based on the respective optimal ignition angle and a respective actual ignition angle of the respective spark plug; Calculating (S3) an n-dimensional hyperplane on which each (n+1)-dimensional point specifies an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs, based on the ignition angle differences; preferably determining (S4) an engine torque model and / or an engine torque hyperplane based on the hyperplane; determining (S5) a specific ignition angle efficiency and / or a specific engine torque based on the calculated hyperplane and / or preferably the specific engine torque model and / or the specific engine torque hyperplane as a function of a specific combination of ignition angle differences of the n spark plugs; and Control (S6) of the engine based on the determined ignition angle efficiency and / or preferably the determined engine torque.

2. Method according to claim 1, wherein the motor is further controlled based on the provided hyperplane and / or the motor torque model and / or the motor torque hyperplane.

3. Computer-implemented method for determining a combination of ignition angles of n spark plugs of an engine, in particular for adjusting n ignition timings in the engine; wherein n > 2, the method comprising the steps: Providing (S11) an n-dimensional hyperplane on which each (n+1)-dimensional point specifies an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs; wherein, on the hyperplane, for each ignition angle efficiency, a plurality of possible combinations of ignition angle differences of the n spark plugs exist on a respective iso-function; Define (S12) a boundary condition by which the multitude of possible combinations of ignition angle differences of the n spark plugs on an iso-function becomes restricted and thus determinable; Determine (S13) a combination of ignition angle differences of the n spark plugs based on a predetermined ignition angle efficiency based on the boundary condition and the iso-function dependent on the predetermined ignition angle efficiency; and Control (S14) of the engine based on the specific combination of ignition angles of the n spark plugs.

4. Method according to claim 3, wherein determining (S13) the combination of ignition angle differences comprises a calculation based on n optimal ignition angles of the n spark plugs and of respective actual ignition angles of the n spark plugs.

5. Method according to claim 3 or 4, wherein providing (S11) the (n+1) dimensional hyperplane comprises: Calculating the n optimal ignition angles of n spark plugs based on speed information and engine load information; Calculating n ignition angle differences based on the respective optimal ignition angle and the respective actual ignition angle of the respective spark plug; and Calculating the n-dimensional hyperplane based on the ignition angle differences.

6. Method according to any one of claims 3 to 5, wherein the hyperplane is provided on the basis of an engine torque model and / or an engine torque hyperplane.

7. Method according to one of claims 3 to 6, wherein the hyperplane is invertible by defining (S12) the boundary condition, in particular in the form of an n-dimensional strategy function.

8. Method according to any one of claims 3 to 7, wherein the boundary condition is selected based on the engine and / or a combustion quality of an engine ignition of the engine at a specific operating point.

9. Method according to any one of claims 3 to 8, wherein the boundary condition is chosen such that the boundary condition defines a strategy function with mathematically monotonic behavior that intersects the iso-function at a single intersection point.

10. Method according to any one of claims 3 to 9, wherein the ignition angle efficiency of the n spark plugs varies based on a respective geometric arrangement of the n spark plugs and / or a type of the n spark plugs and / or an influence of the n spark plugs within a cylinder of the engine.

11. Method according to one of claims 3 to 8, wherein the provision (S11) of the boundary condition is further carried out taking into account a geometric arrangement of the n spark plugs, distinguishing between symmetrical systems in which the n spark plugs are installed geometrically symmetrically and the influence of the respective ignition angle for n ignitions is symmetrical, and asymmetrical systems in which the n spark plugs are installed geometrically asymmetrically.

12. Computer program with program code to execute at least parts of a method according to any one of claims 1 to 11 when the computer program is executed on a computer.

13. Computer-readable data carrier containing program code of a computer program for executing at least parts of a method according to any one of claims 1 to 11 when the computer program is executed on a computer.

14. Device (100), in particular control unit, preferably engine control unit, for determining an ignition angle efficiency and / or an engine torque for controlling an engine, wherein n > 2, wherein the device (100) is configured to perform the following steps: Calculating n optimal ignition angles for n spark plugs of the engine based on speed information and engine load information; Calculating n ignition angle differences based on the respective optimal ignition angle and a respective actual ignition angle of the respective spark plug; Calculating an n-dimensional hyperplane where each (n+1)-dimensional point gives an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs, based on the ignition angle differences; Determining an engine torque model and / or an engine torque hyperplane based on the hyperplane; Determining a specific ignition angle efficiency and / or a specific engine torque based on the calculated hyperplane and / or the specific engine torque model and / or the specific engine torque hyperplane as a function of a specific combination of ignition angle differences of the n spark plugs; and Controlling the engine based on the specified ignition angle efficiency and / or the specified engine torque.

15. Device (100), in particular a control unit, preferably an engine control unit, for determining a combination of ignition angles of n spark plugs of an engine, in particular for adjusting n ignition timings in an engine; wherein n > 2, wherein the device (100) is configured to perform the following steps: Providing an n-dimensional hyperplane on which each (n+1)-dimensional point specifies an ignition angle efficiency for a combination of n ignition angle differences of the n spark plugs; wherein, on the hyperplane, for each ignition angle efficiency, a plurality of possible combinations of ignition angle differences of the n spark plugs exist on a respective iso-function; Defining a boundary condition that restricts and thus makes determinable the multitude of possible combinations of ignition angle differences of the n spark plugs on an iso-function; Determining a combination of ignition angle differences of the n spark plugs based on a predetermined ignition angle efficiency, using the boundary condition and the iso-function dependent on the predetermined ignition angle efficiency; and Controlling the engine based on a specific combination of ignition angles.

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