Method for operating an internal combustion engine of a motor vehicle

Abstract

The invention relates to a method for operating an internal combustion engine (10) of a motor vehicle, in which the internal combustion engine (10) has at least one combustion chamber (22), an injection element (24) associated with the combustion chamber (22) by means of which fuel can be injected into the combustion chamber (22), and a pre-chamber spark plug (28) associated with the combustion chamber (22), which has a pre-chamber (30) fluidically connected to the combustion chamber (22) via several openings (32), into which at least a part of a fuel-air mixture comprising fuel and air can be introduced from the combustion chamber (22) via the openings (32), wherein in a first operating range of the internal combustion engine (10), which is operated in the first operating range with at least one first load and at least one first speed, exactly one injection process is carried out within each working cycle of the internal combustion engine (10).in which exactly a quantity of fuel is introduced into the combustion chamber (22) by means of the injection element (24).

Description

[0001] The invention relates to a method for operating an internal combustion engine of a motor vehicle according to the preamble of claims 1 and 4.

[0002] DE 10 2020 007 477 A1 discloses a method for operating an internal combustion engine for a motor vehicle. Furthermore, DE 10 2018 007 093 A1 discloses a pre-chamber spark plug for a combustion chamber of an internal combustion engine, comprising a pre-chamber with several openings which can be fluidically connected to the combustion chamber via these openings. A fuel-air mixture can be introduced from the combustion chamber into the pre-chamber via these openings. Additionally, DE 10 2019 126 964 A1 discloses a method for operating a spark-ignition four-stroke reciprocating internal combustion engine.

[0003] DE 10 2020 130 836 A1 discloses a method for operating an internal combustion engine of a motor vehicle. The internal combustion engine has at least one combustion chamber and an injection element associated with the combustion chamber, by means of which fuel can be introduced into the combustion chamber. A pre-chamber spark plug is associated with the combustion chamber, which has a pre-chamber fluidically connected to the combustion chamber via several openings, into which at least a portion of a fuel-air mixture comprising fuel and air can be introduced from the combustion chamber via the openings.In a first operating range of the internal combustion engine, which is operated in this range with at least one first load and at least one first speed, exactly one injection process is carried out within each working cycle of the internal combustion engine, in which exactly one quantity of fuel is introduced into the combustion chamber by means of the injection element. In a second operating range of the internal combustion engine, which is operated in this range with at least one second load higher than the first load and / or at least one second speed higher than the first speed, exactly one injection process is carried out within each working cycle of the internal combustion engine, in which exactly one quantity of fuel is introduced into the combustion chamber by means of the injection element.

[0004] German patent DE 10 2022 207 461 A1 discloses a method for operating an internal combustion engine with a pre-chamber spark plug. Measures are taken that lead to an increase in the exhaust gas temperature of the internal combustion engine.

[0005] German patent DE 10 2022 207 299 A1 discloses a method for controlling an internal combustion engine which has a pre-chamber spark plug and a further hook spark plug in a combustion chamber. In a first operating range of the internal combustion engine, combustion in the combustion chamber is initiated by the pre-chamber spark plug, and in a second operating range of the internal combustion engine, combustion is initiated by the hook spark plug.

[0006] The object of the present invention is to provide a method for operating an internal combustion engine of a motor vehicle, such that a particularly advantageous operation of the internal combustion engine can be achieved.

[0007] This problem is solved by a method with the features of claim 1 and by a method with the features of claim 4. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0008] A first aspect of the invention relates to a method for operating an internal combustion engine, also referred to simply as a motor, internal combustion engine, or combustion power unit, of a motor vehicle, also referred to simply as a vehicle. Preferably, the motor vehicle is a car, in particular a passenger car. Preferably, the internal combustion engine is a four-stroke engine. Most preferably, the internal combustion engine is a reciprocating piston engine, i.e., a reciprocating piston machine. Preferably, the method provides that the motor vehicle is driven by means of the internal combustion engine. For example, the internal combustion engine has an output shaft, in particular a crankshaft, via which drive torques for driving the motor vehicle can be provided by the internal combustion engine or are provided in the method.The internal combustion engine, for example, has an engine housing, wherein the output shaft is rotatable about an output shaft axis of rotation relative to the engine housing. In particular, it is provided that in the method the output shaft rotates about the output shaft axis of rotation relative to the engine housing, especially at a speed that is also referred to as the speed of the output shaft or the speed of the internal combustion engine.

[0009] In this process, the internal combustion engine has at least one combustion chamber. The combustion chamber is, for example, partially bounded by a cylinder, which may form the engine housing. Furthermore, the combustion chamber is partially bounded by a piston arranged within the cylinder so as to be translationally movable. The piston is, for example, articulated to the output shaft via a connecting rod, such that translational movements of the piston occurring within the cylinder, relative to the engine housing, can be converted into a rotational movement of the output shaft relative to the engine housing and about the output shaft's axis of rotation. In particular, the piston is translationally movable within the cylinder between a bottom dead center (BDC) and a top dead center (TDC) of the piston.

[0010] Furthermore, it is conceivable that the combustion chamber is partially bounded by a combustion chamber roof, wherein the combustion chamber roof is formed, for example, by a housing element of the internal combustion engine. Preferably, the housing element is designed separately from the engine housing and is connected to the engine housing at least indirectly, and in particular directly. Preferably, the housing element is designed as a cylinder head of the internal combustion engine.

[0011] In this method, the internal combustion engine has an injection element associated with the combustion chamber, which is also referred to as an injection element or can be designed as an injection element. In particular, the injection element is also referred to as an injector. A preferably liquid fuel can be introduced into the combustion chamber by means of the injection element, in particular such that the fuel can be injected, especially directly, into the combustion chamber by means of the injection element.

[0012] In this process, the internal combustion engine also has a pre-chamber spark plug associated with the combustion chamber, which has a pre-chamber fluidically connected to the combustion chamber, also referred to as the main combustion chamber, via several openings in the pre-chamber spark plug. Specifically, the pre-chamber is fluidically connected to the combustion chamber via these openings and otherwise fluidically separated from the combustion chamber. The combustion chamber can be supplied with fuel, particularly bypassing the pre-chamber, by means of the injection element, which allows the fuel to be introduced, particularly by injection, into the combustion chamber, bypassing the pre-chamber. This means that the fuel does not flow into the combustion chamber via the pre-chamber on its way from the injection element.Furthermore, the combustion chamber can be supplied with air, in particular in such a way that the air, also referred to as fresh air or combustion air, can be introduced into the combustion chamber, especially bypassing the pre-chamber. This means that the air does not flow into the combustion chamber via the pre-chamber on its way there. In particular, it is provided that in the process the combustion chamber is supplied with fuel, especially bypassing the pre-chamber, by means of the injection element, especially by injecting and, most importantly, directly injecting the fuel into the combustion chamber. It is also provided, for example, that in the process the combustion chamber is supplied with air by introducing the air into the combustion chamber, especially bypassing the pre-chamber.By supplying the combustion chamber with the preferably liquid fuel and air, a fuel-air mixture, also simply referred to as a mixture, can be formed, particularly within each operating cycle of the internal combustion engine. This mixture comprises the air with which the combustion chamber can be supplied or is supplied, and the fuel with which the combustion chamber can be supplied or is supplied. In particular, within each operating cycle of the internal combustion engine, at least a portion of the fuel-air mixture comprising the fuel and air can be introduced or is introduced from the combustion chamber into the openings of the pre-chamber. Preferably, each operating cycle of the internal combustion engine comprises exactly two complete revolutions of the output shaft and thus, for example, exactly 720 degrees of crankshaft angle (°CA).

[0013] For example, the pre-chamber spark plug is designed to generate at least one spark, or exactly one, within the pre-chamber during each combustion cycle. This spark ignites the fuel-air mixture flowing into the pre-chamber through its openings. This results in so-called "burning torches" that pass through the openings and into the combustion chamber, igniting the remaining mixture in the combustion chamber, which is then combusted. This expansion of the mixture drives, for example, the pistons and, via the connecting rod, the output shaft. This rotation of the output shaft relative to the engine block occurs around its axis of rotation, allowing the internal combustion engine to provide, or potentially provide, the required output torque.To generate the ignition spark, the pre-chamber spark plug has at least or exactly two electrodes: a first electrode and a second electrode. The first electrode is, for example, a so-called center electrode. The second electrode is, for example, a so-called ground electrode. The electrodes generate the ignition spark, particularly in an ignition zone located within the pre-chamber, and specifically via a so-called ignition path, thereby igniting the fuel-air mixture flowing into the pre-chamber.

[0014] In order to achieve a particularly advantageous operation of the internal combustion engine, the invention provides that, in a first operating range of the internal combustion engine, which is operated in the first operating range with at least one first load and at least one first rotational speed, exactly one injection process is carried out within each working cycle of the internal combustion engine, in which exactly one quantity of fuel is introduced into the combustion chamber by means of the injection element, in particular injected and, more specifically, directly injected. The at least one first rotational speed of the internal combustion engine is understood to be at least one first rotational speed of the output shaft, which rotates in the first operating range at at least one first rotational speed about the output shaft axis of rotation relative to the engine housing.In other words, at least one first rotational speed of the internal combustion engine, and thus of the output shaft, is at least one first value of the aforementioned rotational speed at which the output shaft rotates around the output shaft axis in the first operating range relative to the engine housing.

[0015] Furthermore, according to the invention, in a second operating range of the internal combustion engine, which in this second operating range is operated with at least one higher load and / or a higher second speed than the first, exactly one injection process is carried out within each operating cycle of the internal combustion engine, in which exactly one quantity of fuel is introduced into the combustion chamber by means of the injection element, in particular injected and, most especially, directly injected. The preceding and following descriptions relating to at least one first speed can readily be applied to at least one second speed and vice versa.This means that the "at least one second speed" of the internal combustion engine refers to at least one second speed of the output shaft, which rotates around its axis of rotation relative to the engine housing at this second speed in the second operating range. Thus, the "at least one second speed" is at least a second value of the previously mentioned speed at which the output shaft rotates around its axis of rotation relative to the engine housing in the second operating range. Since, for example, the second speed is greater than the first speed, the second value is also greater than the first value. In other words, for example, in the second operating range, the output shaft rotates around its axis of rotation relative to the engine housing faster than in the first operating range.

[0016] Furthermore, according to the invention, the injection process is carried out later in the second operating range than in the first operating range within the respective combustion cycle to cool at least a portion of the pre-chamber spark plug. This means that the respective quantity is introduced, in particular injected, and especially directly injected, into the combustion chamber later in the second operating range than in the first operating range within the respective combustion cycle. This later introduction of the quantity, and thus of the fuel, into the combustion chamber compared to the first operating range allows at least the portion of the pre-chamber spark plug to be cooled advantageously. This prevents excessive temperatures of the pre-chamber spark plug, thus ensuring, as will be explained in more detail below, efficient operation of the internal combustion engine.

[0017] Preferably, the respective injection process is an injection process, also referred to as injection, fuel injection, or fuel injection process. Most preferably, the respective injection process is direct fuel injection, also referred to as direct injection, direct injection process, or direct fuel injection process. In direct injection, the fuel is injected directly into the combustion chamber by means of the injection element. The respective operating range is also referred to as the respective operating state of the internal combustion engine.

[0018] The aforementioned section of the pre-chamber spark plug can refer to an electrode area, where, for example, at least one electrode is at least partially located. It has been found that this electrode area can heat up considerably during operation of the internal combustion engine if no appropriate countermeasures are taken. Furthermore, it has been found that the temperature of the electrode area depends on the load and engine speed. The temperature of the electrode area increases with higher load and higher engine speed.It has been found that under high load and high engine speed, or under high load and low engine speed, very high temperatures can occur in the electrode area, particularly in the center electrode, an insulator surrounding the center electrode, a so-called breathing space around the insulator, a ground electrode, and / or in an area around the ground electrode and / or in an area of ​​the pre-chamber spark plug cap, resulting in hot zones, also known as hotspots. For example, the openings in the aforementioned cap are designed such that the cap at least partially, in particular at least predominantly and thus at least more than halfway, or even completely, confines the pre-chamber. In particular, each opening is designed as a through-hole.At such a hotspot, the mixture in the vicinity of the respective hotspot can ignite spontaneously, particularly without the influence of the ignition spark, a phenomenon also known as pre-ignition. Such pre-ignition can lead to excessive stress or even damage to the internal combustion engine, making it desirable to prevent such pre-ignition. This is now easily achieved by the invention, as it utilizes existing components and processes to cool at least the portion of the pre-chamber spark plug, thereby preventing the formation of hotspots and thus undesirable pre-ignition.For this purpose, in the second operating range, the injection process is carried out later within the respective operating cycle compared to the first operating range, so that in the second operating range, the quantity of fuel (also referred to as the fuel quantity) is introduced into the combustion chamber later than in the first operating range within the respective operating cycle. In other words, in the second operating range, the injection process is carried out at a later time within the respective operating cycle compared to the first operating range. Thus, in the second operating range, the injection process begins later than in the first operating range within the respective operating cycle, and, most preferably, the injection process ends later in the second operating range compared to the first operating range within the respective operating cycle.

[0019] Preferably, in the second operating state, compared to the first operating state, the injection process is carried out shortly before the piston's top dead center (TDC) within the respective operating cycle, so that, for example, in the second operating range, compared to the first operating range, the injection process begins shortly before the piston's top dead center within the respective operating cycle. The respective quantity of fuel is also referred to as the respective fuel quantity, mass, or fuel mass, or the respective quantity of fuel is a respective fuel mass, also referred to as the fuel mass.It was found that by performing the insertion process later, or later compared to the first operating range, effective cooling of the critical part, especially the electrode area, of the pre-chamber spark plug can be achieved, so that excessively hot spots and thus undesirable pre-ignitions and resulting excessive loads and damage to the internal combustion engine can be effectively avoided.Since, in the second operating range within each combustion cycle of the internal combustion engine, only one injection process is performed, the entire fuel mass is introduced into the combustion chamber later in this range compared to the first operating range within each combustion cycle. This injection, and especially direct injection, allows for advantageous cooling of the pre-chamber spark plug, particularly the electrode area. The invention makes it possible to cool at least this portion of the pre-chamber spark plug without special, separate cooling measures, thus enabling particularly efficient operation of the internal combustion engine in a space-saving, weight-efficient, and cost-effective manner. The invention also helps to avoid excessive stress and damage to the internal combustion engine.Furthermore, the invention allows for the avoidance of load-relevant interventions, which are noticeable to persons inside the vehicle such as the driver, to prevent pre-ignition, thus ensuring a particularly advantageous operation of the internal combustion engine.

[0020] It is evident that the internal combustion engine operates selectively in either the first or the second operating range, depending on its speed and load. If the speed of the internal combustion engine, i.e., the output shaft, exceeds a predefined threshold value and / or the load exceeds a predefined limit value, the engine operates in the second operating range. If the speed of the internal combustion engine is less than or equal to the threshold value and the load is less than or equal to the limit value, the engine operates in the first operating range.If the internal combustion engine is operated in the second operating range, the engine speed and / or load is greater than in the first operating range, and in the second operating range, the respective engagement process within the respective work cycle is carried out later than in the first operating range. The invention thus provides for map-dependent operation, in particular map-dependent control or map-dependent regulation, of the internal combustion engine, since the engine is selectively operated in either the first or the second operating range depending on its engine speed and load, and thus depending on its operating map.

[0021] It was found that by performing the insertion process later, the fuel introduced into the combustion chamber by means of the insertion process, particularly the injected and especially the directly injected fuel, and thus the quantity of fuel introduced into the combustion chamber by the later insertion process, can advantageously flow through the openings into the pre-chamber and there advantageously cool at least the portion of the pre-chamber spark plug. In particular, this portion is a region in which the first electrode and / or the second electrode are each at least partially located. Thus, by the later insertion process, at least a respective region of the electrodes and / or a region around the electrodes can be advantageously cooled. In particular, this portion is located in the pre-chamber.It was found that the cooling of the pre-chamber spark plug, or at least of the part of the pre-chamber spark plug, which can be effected by the invention and is also referred to as cooling, is a localized and time-limited cooling, which can ensure that a temperature required for self-ignition or pre-ignition is not reached in a critical area, so that the formation of undesirable hotspots and thus engine-damaging pre-ignitions can be prevented.

[0022] To achieve particularly advantageous operation of the internal combustion engine, one embodiment of the first aspect of the invention provides that the quantity introduced into the combustion chamber in the second operating range during the respective injection process within the respective working cycle differs from the quantity introduced into the combustion chamber in the first operating range during the respective injection process within the respective working cycle. This allows at least the portion of the pre-chamber spark plug to be cooled advantageously. Furthermore, it prevents any noticeable interference with the operation of the internal combustion engine by persons inside the vehicle, thus enabling particularly advantageous drivability and therefore advantageous operation of the internal combustion engine.

[0023] In order to effectively and efficiently cool at least the pre-chamber spark plug section and thereby achieve advantageous operation of the internal combustion engine, a further embodiment of the first aspect provides that the quantity introduced, in particular injected, and especially directly injected, into the combustion chamber in the second operating range during the respective injection process carried out within the respective working cycle is greater or less than the quantity introduced, in particular injected, and especially directly injected, into the combustion chamber in the first operating range during the respective injection process carried out within the respective working cycle.

[0024] A second aspect of the invention relates to a method for operating an internal combustion engine of a motor vehicle, also referred to simply as a vehicle. In the method according to the second aspect of the invention, the internal combustion engine comprises at least a combustion chamber, an injection element associated with the combustion chamber by means of which a fuel, in particular a liquid, can be introduced into the combustion chamber, and a pre-chamber spark plug associated with the combustion chamber, which has a pre-chamber fluidically connected to the combustion chamber via several openings, into which at least a portion of a fuel-air mixture comprising fuel and air can be introduced from the combustion chamber via the openings. Advantages and advantageous embodiments of the first aspect of the invention are to be regarded as advantages and advantageous embodiments of the second aspect of the invention, and vice versa.

[0025] In order to achieve a particularly advantageous operation of the internal combustion engine, the second aspect of the invention provides that in a first operating range of the internal combustion engine, which is operated in the first operating range with at least one first load and at least one first speed, at least or exactly two successive and temporally spaced injection processes, namely a first injection process and a second injection process, are carried out within each working cycle of the internal combustion engine, in which exactly a respective quantity of fuel is introduced into the combustion chamber by means of the injection element, in particular injected and, most especially, directly injected.

[0026] In the second aspect of the invention, it is further provided that in a second operating range of the internal combustion engine, which in the second operating range is operated with at least a second load higher than the first load and / or with a second speed higher than the first speed, at least or exactly two successive and temporally spaced injection processes, namely a third injection process and a fourth injection process, are carried out within a respective working cycle of the internal combustion engine, in which exactly a respective quantity of fuel is introduced into the combustion chamber by means of the injection element.

[0027] The second aspect of the invention further provides that, for cooling at least a portion of the pre-chamber spark plug, the last insertion process within each operating cycle is performed later in the second operating cycle than in the first operating cycle. This means that, within each operating cycle, the fourth insertion process is performed later in the second operating cycle than the second insertion process in the first operating cycle.By performing the fourth insertion process later than the respective second insertion process, at least the part of the pre-chamber spark plug can be cooled effectively and efficiently, thus advantageously avoiding excessively hot areas of the pre-chamber spark plug and resulting undesirable effects such as pre-ignition, excessive loads on the internal combustion engine and damage to the internal combustion engine.

[0028] As with the first aspect of the invention, the second aspect of the invention also provides for speed- and load-dependent, and thus map-dependent, control or regulation of the internal combustion engine, since the internal combustion engine is selectively operated in either the first operating range or the second operating range depending on its load and speed, particularly with regard to the respective injection process. In other words, both the first and second aspects of the invention involve a speed- and load-dependent variation of the injection process, i.e., a variation dependent on the speed and load of the internal combustion engine, thereby enabling advantageous operation of the internal combustion engine.

[0029] In order to achieve a particularly advantageous operation of the internal combustion engine, in one embodiment of the second aspect of the invention it is provided that the sum of the quantities introduced into the combustion chamber in the second operating range in the respective injection processes carried out within the respective working cycle differs from the sum of the quantities introduced into the combustion chamber in the first operating range in the respective injection processes carried out within the respective working cycle.

[0030] It has proven particularly advantageous if the sum of the quantities introduced into the combustion chamber during the respective injection processes within the second operating range, within the respective working cycle, is greater or less than the sum of the quantities introduced into the combustion chamber during the respective injection processes within the first operating range, within the respective working cycle. This prevents excessively hot spots on the pre-chamber spark plug, thus enabling particularly efficient operation of the internal combustion engine.

[0031] A further embodiment of the second aspect of the invention is characterized in that the quantity introduced into the combustion chamber during the respective fourth injection process is in a range of 1% to 20% inclusive, and in particular in a range of 3% to 10% inclusive, of the quantity introduced into the combustion chamber during the respective third injection process. The respective injection processes carried out in the second operating range within the respective operating cycle of the internal combustion engine, i.e., the third injection process and the fourth injection process, are spaced apart in time and sequential, such that the respective third injection process ends before the respective fourth injection process begins.For example, the quantity introduced into the combustion chamber during the respective third injection process is also referred to as the third quantity or third sub-quantity, and the quantity introduced into the combustion chamber during the respective fourth injection process is also referred to as the fourth quantity or fourth sub-quantity. It is preferably provided that the fourth sub-quantity is in the range of 1% to 20% inclusive, and particularly in the range of 3% to 10% inclusive, of the third sub-quantity. This allows for advantageous cooling of the pre-chamber spark plug. Furthermore, undesirable load-related interventions perceptible to persons in the vehicle's interior, such as the driver, can be avoided, thus ensuring particularly efficient operation of the internal combustion engine.

[0032] In order to achieve a particularly advantageous operation of the internal combustion engine, an embodiment of the invention applicable to both the first and second aspects provides that the openings cause a tumble-like flow of the fuel-air mixture entering the pre-chamber through the openings. This is already described, for example, in DE 10 2020 007 477 A1.

[0033] In a non-inventive method for operating an internal combustion engine of a motor vehicle, also simply referred to as a vehicle, the interior of which is formed, for example, by a structure designed, in particular, as a self-supporting body, the internal combustion engine has at least one combustion chamber, an injection element associated with the combustion chamber by means of which a fuel, in particular liquid, can be introduced into the combustion chamber, in particular injected and, most especially, directly injected, and a pre-chamber spark plug associated with the combustion chamber, which has a pre-chamber fluidically connected to the combustion chamber via several openings and, for example, otherwise fluidically separated from the combustion chamber. At least a portion of a fuel-air mixture comprising fuel and air can be introduced from the combustion chamber into the pre-chamber via the openings.

[0034] In order to enable the operation of the internal combustion engine, it is provided that in a first operating range of the internal combustion engine, which in the first operating range is operated with at least one first load and at least one first speed, exactly one injection process is carried out within each working cycle of the internal combustion engine, in which exactly one quantity of fuel is introduced into the combustion chamber by means of the injection element.Furthermore, it is provided that, in order to cool at least a partial area of ​​the pre-chamber spark plug in a second operating range of the internal combustion engine, which in the second operating range is operated with at least a second load higher than the first load and / or with at least a second speed higher than the first speed, at least or exactly two successive and temporally spaced injection processes are carried out within a respective working cycle of the internal combustion engine, namely a first injection process and a second injection process, in which exactly a respective quantity of fuel is introduced into the combustion chamber by means of the injection element, in particular injected and most especially directly injected.The quantity introduced into the combustion chamber during the first injection process in the second operating range within the respective combustion cycle is also referred to as the first quantity, and the quantity introduced into the combustion chamber during the second injection process in the second operating range within the respective combustion cycle is also referred to as the second quantity. The first quantity is also referred to as the first sub-quantity, first mass, or first fuel mass, and the second quantity is also referred to as the second sub-quantity, second mass, or second fuel mass.The first insertion process carried out in the second operating area within the respective work cycle does not necessarily have to be the first insertion process carried out, i.e., the very first insertion process, so that it would be conceivable in principle that at least or exactly one further insertion process is carried out in the second operating area within the respective work cycle before the first insertion process.However, it is intended that the first injection process carried out in the second operating range within the respective work cycle is the first injection process carried out within the respective work cycle and thus the very first injection process, so that it is intended that no other, further injection process is carried out in the second operating range within the respective work cycle before the first injection process, in which fuel is introduced into the combustion chamber by means of the injection element.

[0035] In principle, it is provided within the framework of the present disclosure that ordinals also referred to as ordinal numbers, such as "first", "first", "first", "second", "second", "second", etc., are initially only used to be able to clearly refer to terms to which the ordinals refer, whereby these ordinals do not necessarily indicate a temporal or other order or a number of terms, unless this is explicitly described.

[0036] The internal combustion engine operates in a speed- and load-dependent manner, as it is selectively operated in either the first or second operating range depending on its speed and load. If the engine speed exceeds a threshold and / or the load exceeds a limit, the engine operates in the second operating range, thus switching from the first to the second. Operating the internal combustion engine in the second operating range involves a distribution of fuel, also referred to as fuel mass, compared to the first operating range.This means the following: Since in the first operating range, within each working cycle of the internal combustion engine, exactly one injection process is carried out, and thus exactly one quantity of fuel is introduced into the combustion chamber, exactly one total quantity of fuel, also referred to as or represented as a total mass, is introduced into the combustion chamber in the first operating range within each working cycle. Since in the second operating range, within each working cycle, at least or exactly two injection processes are carried out, by which a respective quantity of fuel, also referred to or represented as a mass, is introduced into the combustion chamber, at least or exactly two quantities of fuel, namely a first quantity and a second quantity, are introduced into the combustion chamber in the second operating range within each working cycle.The aforementioned total quantity is also referred to as the first total quantity. The first quantity introduced into the combustion chamber during the first injection process in the second operating range within the respective operating cycle, and the second quantity introduced into the combustion chamber during the second injection process in the second operating range within the respective operating cycle, together constitute a second total quantity, which is also referred to as the second total mass of fuel. In principle, it would be conceivable for the second total quantity to be larger or smaller than the first total quantity. However, it is designed so that the second total quantity equals the first total quantity and vice versa, resulting in equal total quantities. The first and second quantities are introduced into the combustion chamber sequentially and with a time interval between them.This means that the first injection process ends before the second injection process begins. The first quantity is also referred to as the first partial quantity, which is also called the first partial mass, or simply the first partial mass of the fuel. The second quantity is also referred to as the second partial quantity, which is also called the second partial mass of the fuel. Thus, the total first quantity is divided into at least two, or exactly two, partial quantities. This allows for cooling, also known as cooling, of at least part of the pre-chamber spark plug, thereby advantageously preventing the formation of undesirable hot zones and thus undesirable pre-ignitions or resulting excessive stress on the internal combustion engine and damage to the engine.

[0037] In order to effectively and efficiently cool at least the pre-chamber spark plug section, the sum of the quantities introduced into the combustion chamber during the respective injection events within the second operating range (i.e., the sum of the first and second quantities) is designed to differ from the quantity introduced into the combustion chamber during the respective injection event within the first operating range. Thus, the second total quantity is designed to differ from the first total quantity.

[0038] If the sum of the quantities introduced into the combustion chamber during the respective injection processes within the second operating range is greater or less than the quantity introduced into the combustion chamber during the respective injection process within the first operating range, then the second quantity can be cooled. This allows at least the portion of the pre-chamber spark plug to be cooled, thus advantageously avoiding undesirable effects such as pre-ignition, excessive stress, and damage to the internal combustion engine. This enables the operation of the internal combustion engine.

[0039] The aforementioned first insertion process, which is carried out in the second operating area within the respective work cycle, is carried out in the second operating area within the respective work cycle before the aforementioned second insertion process, which is carried out in the second operating area within the respective work cycle after the first insertion process.

[0040] If the quantity introduced into the combustion chamber during the respective second injection process is within a range of 1% to 20% inclusive, and in particular within a range of 3% to 10% inclusive, of the quantity introduced into the combustion chamber during the respective first injection process, then the second quantity is within a range of 1% to 20% inclusive, and in particular within a range of 3% to 10% inclusive, of the first quantity. In other words, it is intended that the second sub-quantity is within a range of 1% to 20% inclusive, and in particular within a range of 3% to 10% inclusive, of the first sub-quantity. This allows at least the pre-chamber spark plug area to be cooled effectively and efficiently.At the same time, noticeable interventions in the operation of the internal combustion engine can be carried out by persons inside the vehicle, such as the driver, so that a particularly smooth operation of the internal combustion engine can be ensured.

[0041] In order to at least cool the pre-chamber spark plug area and thus enable the operation of the internal combustion engine, it is provided that in the second operating range, the respective second injection process carried out within the respective working cycle is the last injection process carried out within the respective working cycle, so that in the second operating range, no further injection process for introducing the fuel into the combustion chamber follows a second injection process within the respective working cycle.

[0042] Further advantages, features, and details of the invention will become apparent from the following description of a preferred embodiment and from the drawing. The features and combinations of features mentioned above in the description, as well as those mentioned below in the figure description and / or shown in the figures alone, can be used not only in the combinations specified, but also in other combinations or individually, without departing from the scope of the invention. This is shown in the following: Fig. 1. Partially a schematic sectional view of an internal combustion engine of a motor vehicle; Fig. 2. A diagram illustrating a method for operating the internal combustion engine; and Fig. 3. Another diagram to further illustrate the procedure.

[0043] In the figures, identical or functionally equivalent elements are provided with the same reference symbols.

[0044] Fig. Figure 1 shows a partial schematic sectional view of an internal combustion engine 10 of a motor vehicle, also referred to simply as a vehicle. The internal combustion engine 10 is designed as a reciprocating piston engine, that is, as a piston engine. The internal combustion engine 10 has an engine housing 12, which is designed, for example, as a crankcase, in particular as a cylinder crankcase. The engine housing 12 forms or delimits a cylinder 14 of the internal combustion engine 10. The internal combustion engine 10 also has a housing element 16, which in this case is designed as a cylinder head. The housing element 16 is designed separately from the engine housing 12 and connected to the engine housing 12. The housing element 16 forms a combustion chamber roof 18.The internal combustion engine 10 also has a piston 20 arranged translationally within the cylinder 14, which is translationally movable within the cylinder 14 and relative to the engine housing 12. The piston 20 is translationally movable back and forth between a bottom dead center (BDC) and a top dead center (TDC). The internal combustion engine 10 also has at least one combustion chamber 22, which is partially bounded by the piston 20, partially by the combustion chamber roof 18, and partially by the cylinder 14. The combustion chamber 22 is also referred to as the main combustion chamber. In the combustion chamber 22, in particular, an injection element 24 is provided, by means of which a preferably liquid fuel can be introduced into the combustion chamber 22, such that the fuel can be injected directly into the combustion chamber 22 by means of the injection element 24. Fig. As can be seen from Figure 1, the injection element 24 can eject the preferably liquid fuel, forming at least one or more injection jets 26, and thereby inject it directly into the combustion chamber 22. This means that the respective injection jet 26 is formed by the fuel that is ejected from the injection element 24 and thereby injected directly into the combustion chamber 22. A pre-chamber spark plug 28 of the internal combustion engine 10 is also associated with the combustion chamber 22. The pre-chamber spark plug 28 has a pre-chamber 30, which is fluidically connected to the combustion chamber 22 via an opening 32 of the pre-chamber spark plug 28 designed as a through-opening and is preferably otherwise, and in particular completely, fluidically separated from the combustion chamber 22. The pre-chamber spark plug 28 has at least or exactly two electrodes, namely a first electrode 34 and a second electrode 36.For example, electrode 34 is a center electrode. For example, electrode 36 is a ground electrode. At least partial sections of electrodes 34 and 36 are located in the prechamber 30. By means of electrodes 34 and 36, the prechamber spark plug 28 can generate and thus provide a spark in the prechamber 30.

[0045] The combustion chamber 22 is also associated with at least one gas exchange valve designed as an inlet valve 38, through which air, also referred to as fresh air or combustion air, can be introduced into the combustion chamber 22. The air that can be introduced or is introduced into the combustion chamber 22 via the inlet valve 38 is in Fig. Figure 1 is schematically illustrated by an arrow 40. Arrow 40 illustrates a tumble-shaped airflow, also known as a tumble flow. By introducing air into the combustion chamber and injecting fuel into the combustion chamber 22, a fuel-air mixture, also simply called a mixture, can be formed, i.e., generated, in the combustion chamber 22. This fuel-air mixture comprises the air introduced into the combustion chamber 22 and the fuel injected directly into the combustion chamber 22. At least a portion of the mixture can be introduced from the combustion chamber 22 into the pre-chamber 30 via the openings 32. The mixture introduced into the pre-chamber 30 via the openings 32, i.e., the aforementioned portion of the mixture originating from the main combustion chamber and introduced into the pre-chamber 30 via the openings 32, is in Fig. 1 illustrated by an arrow 42. The arrow 42 shows that the pre-chamber spark plug 28, in particular the openings 32, is designed to cause a tumble-shaped flow of the mixture flowing into the pre-chamber 30 via the openings 32 and thus being introduced.

[0046] The following will be based on Fig. Sections 1 to 3 describe a method for operating the internal combustion engine 10. In particular, the method involves operating the internal combustion engine 10 in its fired mode. Specifically, the method involves, for example, powering the motor vehicle by means of the internal combustion engine 10. During each operating cycle of the internal combustion engine 10, the fuel and air are introduced into the combustion chamber 22 as described, so that the mixture mentioned above is formed during the respective operating cycle.

[0047] The internal combustion engine 10 has an output shaft, preferably designed as a crankshaft and not shown in the figures, which is rotatable about an output shaft axis of rotation relative to the engine housing 12. In particular, it is provided that in this method the output shaft rotates about the output shaft axis of rotation relative to the engine housing 12. The piston 20 is articulated to the output shaft via a connecting rod (not shown in the figures), so that the translational movements of the piston 20 in the cylinder 14 can be converted into a rotational movement of the output shaft about the output shaft axis of rotation and relative to the engine housing 12. Each working cycle of the internal combustion engine 10 comprises exactly two complete revolutions of the output shaft and thus exactly 720 degrees of crank angle (°CA).

[0048] In the embodiment shown in the figures, the internal combustion engine 10 is operated in a first operating range in which the internal combustion engine 10 is operated with at least one first load and at least one first rotational speed of the output shaft and thus of the internal combustion engine 10. This means that in the first operating range the output shaft rotates at at least one first rotational speed about the output shaft axis of rotation relative to the engine housing 12.In the first operating range, within the respective working cycle of the internal combustion engine 10, exactly one injection process, also referred to as injection process, injection or direct fuel injection, is carried out by means of the injection element 24, in which exactly one quantity of fuel, also referred to as fuel quantity, mass or fuel mass or first total quantity, is directly injected and thereby introduced into the combustion chamber 22 by means of the injection element 24.

[0049] To ensure particularly advantageous operation of the internal combustion engine 10, the method involves operating the internal combustion engine 10 in a second operating range. In this range, the engine 10 operates with at least one second load that is higher than the first load and / or with at least one second speed that is higher than the first speed. This means that in the second operating range of the internal combustion engine 10, the second load is greater than the first load and / or the output shaft rotates about its axis of rotation relative to the engine housing 12 at a second speed that is higher than the at least one first speed.In order to advantageously cool at least a portion of the pre-chamber spark plug 28 and thus prevent undesirable pre-ignition, at least or preferably exactly two successive and temporally spaced injection processes, also referred to as injection events, direct injections, or fuel direct injections, are carried out in the second operating range within the respective operating cycle of the internal combustion engine 10. These injection processes are a first injection process and a second injection process, in which exactly a specific quantity of fuel is injected directly into the combustion chamber 22 by means of the injection element 24. The quantity that is injected directly into the combustion chamber 22 in the respective injection process is also referred to as the first quantity, first mass, first fuel mass, first partial mass, or first partial quantity.The quantity injected directly into combustion chamber 22 during the respective second injection process is also referred to as the second quantity, second mass, second fuel mass, second partial mass, or second partial quantity. The first quantity and the second quantity together constitute, for example, a second total quantity. In principle, it would be conceivable for the second total quantity to be larger or smaller than the first total quantity. Preferably, however, the second total quantity corresponds to the first total quantity and vice versa, so that the total quantities are preferably equal. Thus, it is provided that in the second operating range, compared to the first operating range, the first total quantity is divided into the partial quantities.In other words, in the second operating range, the fuel injection process is divided into two injection operations, namely the first injection operation and the second injection operation, which are sequential and spaced apart in time. This means that the first injection operation ends before the second injection operation begins. Put another way, the second injection operation begins after the first injection operation has ended.

[0050] Preferably, the second quantity is in a range of 1% to 20% inclusive, and particularly in a range of 3% to 10% inclusive, of the first quantity. This allows at least the partial area of ​​the pre-chamber spark plug 28 to be advantageously cooled. Preferably, this partial area is an electrode area arranged in the pre-chamber 30, in which the electrodes 34 and 36 are arranged.

[0051] Fig. Figure 2 shows a diagram where time is plotted on the abscissa (44). The ordinate (46) of the diagram in Fig. Figure 2 shows the temperature of the aforementioned subsection of the prechamber spark plug 28. For example, the subsection of the prechamber spark plug 28 is or comprises at least a portion of the electrode 34, which is designed, for example, as a center electrode, located, for example, in the prechamber 30. A time series 48 illustrates the temperature of the subsection at a first value of the output shaft rotational speed, where the first value is, for example, 6000 revolutions per minute. A time series 50 illustrates the temperature of the subsection at a second value of the output shaft rotational speed, which is lower than the first value, where the second value is, for example, 4000 revolutions per minute.A curve 52 illustrates, for example, the temperature of the sub-area at a third value of the output shaft rotational speed that is lower than the first and second values, where the third value is, for example, 2000 revolutions per minute. A dashed line 54 illustrates a point in time at which, for example, in the second operating range within the respective working cycle of the internal combustion engine 10, the respective second insertion process begins or ends.Preferably, it is provided that in the second operating range of the internal combustion engine 10, the second injection process carried out within the respective working cycle is the last injection process carried out within the respective working cycle of the internal combustion engine 10, so that preferably no further injection process follows the second injection process in the second operating range within the respective working cycle of the internal combustion engine 10. Thus, the second injection process is also referred to as the last injection.If, for example, the last injection is considered to occur at the same time at each rotational speed of the output shaft and thus of the internal combustion engine 10, specifically in degrees of crankshaft angle before top dead center, and especially before top dead center for ignition, then a portion of the injected and vaporized quantity enters the pre-chamber spark plug 28 through the openings 32 of the pre-chamber spark plug 28, which are designed, for example, as transfer ports and are also referred to as transfer ports, sooner or later, depending on the rotational speed. Under the same load, the temperature of this portion is higher at higher rotational speeds than at lower rotational speeds.When the fuel-air mixture enters the injection area, it cools the area, including, for example, the center electrode and the surrounding area, because the fuel mixture is colder than the combustion air, primarily due to the fuel's enthalpy of vaporization. After ignition, the injection area then heats up again to a higher temperature due to the combustion process. The degree of temperature reduction in the injection area, and thus, for example, in the center electrode, depends on factors such as the injected quantity of fuel, the initial temperature of the injection area or the center electrode, the calorific value of the fuel, the engine speed, and possibly at least one or more other factors.

[0052] Fig. Figure 3 shows another diagram, on whose abscissa 56 time is plotted. On the ordinate 58, the temperature of the sub-area is plotted. A dashed line 60 illustrates a first point in time at which, in the second operating range within the respective working cycle of the internal combustion engine 10, the second and preferably last injection process ends or begins. A dashed line 62 illustrates a second point in time at which, in the second operating range within the respective working cycle of the internal combustion engine 10, the respective second and preferably last injection process ends or begins. A dashed line 64 illustrates a third point in time at which, in the second operating range within the respective working cycle of the internal combustion engine 10, the respective second and preferably last injection process ends or begins.It is evident that the second point in time within the respective operating cycle is later than the first point in time, and the third point in time within the respective operating cycle is later than both the first and the second point in time. A time curve 66 illustrates the temperature of the sub-area, whereby the curve 66 results from the first point in time, that is, from when the second injection process begins or ends at the first point in time within the second operating range of the respective operating cycle. A curve 68 illustrates the temperature of the sub-area, wherein the temperature of the sub-area illustrated by the curve 68 results from the second point in time, that is, from when the second injection process begins or ends at the second point in time within the second operating range of the respective operating cycle of the internal combustion engine 10.Finally, curve 70 illustrates the temperature of the sub-area, whereby the temperature of the sub-area illustrated by curve 70 results from the third point in time, namely when, in the second operating range within the respective operating cycle of the internal combustion engine 10, the second injection process begins or ends at the third point in time. In simplified terms, the respective point in time is the respective point in time of the second or last injection. From . Fig. 3. It is evident that the respective point in time at which the second and preferably last insertion process is carried out in the second operating range within the respective work cycle can be variable, and in particular is varied. For example, the point in time at which the respective second and preferably last insertion process begins or ends in the second operating range within the respective work cycle is varied, in particular depending on the speed and / or the load of the internal combustion engine 10.

[0053] Out of Fig.3. The following is particularly evident: At the same rotational speed, the following can be determined, in particular for all rotational speeds: either by means of the speed- and load-dependent, and thus map-controlled or map-regulated, last injection, or by carrying out exactly one injection process in the second operating range within the respective working cycle using the injection element 24, which is carried out later compared to the first operating range within the respective working cycle. This allows the time at which the minimum temperature reached in the sub-range due to cooling, and thus, for example, at the center electrode, should occur. This will logically occur at a time at which, without an additional injection such as the second injection process, the maximum temperature of the sub-range, and thus, for example, at the center electrode, would be reached.The degree of cooling of the sub-area can be influenced by the size of the injected quantity. Reference symbol list 10 Internal combustion engine 12 Motor housings 14 cylinders 16 Housing element 18 Combustion chamber roof 20 pistons 22 Combustion chamber 24 insertion element 26 injection jet 28 Pre-chamber spark plug 30 Antechamber 32 Opening 34 electrode 36 electrode 38 Inlet valve 40 Arrow 42 Arrow 44 Abscissa 46 ordinates 48 Course 50 Course 52 Course 54 dashed line 56 Abscissa 58 ordinates 60 dashed line 62 dashed line 64 dashed line 66 Course 68 Course 70 Course

Claims

[1] Method for operating an internal combustion engine (10) of a motor vehicle, in which the internal combustion engine (10) has at least one combustion chamber (22), an injection element (24) associated with the combustion chamber (22) by means of which a fuel can be introduced into the combustion chamber (22), and a pre-chamber spark plug (28) associated with the combustion chamber (22), which has a pre-chamber (30) fluidically connected to the combustion chamber (22) via several openings (32), into which at least a part of a fuel-air mixture comprising fuel and air can be introduced from the combustion chamber (22) via the openings (32), characterized by , that: - in a first operating range of the internal combustion engine (10), which in the first operating range is operated with at least one first load and at least one first speed, within each working cycle of the internal combustion engine (10) exactly one injection process is carried out in which exactly one quantity of fuel is introduced into the combustion chamber (22) by means of the injection element (24); - in a second operating range of the internal combustion engine (10), which in the second operating range is operated with at least a second load higher than the first load and / or with at least a second speed higher than the first speed, exactly one injection process is carried out within each working cycle of the internal combustion engine (10), in which exactly one quantity of fuel is introduced into the combustion chamber (22) by means of the injection element (24); and - to cool at least a part of the pre-chamber spark plug (28), the respective insertion process is carried out later in the second operating range than in the first operating range within the respective working cycle. [2] Method according to claim 1, characterized by , that the quantity introduced into the combustion chamber (22) in the second operating area during the respective introduction process carried out within the respective work cycle differs from the quantity introduced into the combustion chamber (22) in the first operating area during the respective introduction process carried out within the respective work cycle. [3] Method according to claim 2, characterized by, that the quantity introduced into the combustion chamber (22) in the second operating area during the respective introduction process carried out within the respective work cycle is greater than the quantity introduced into the combustion chamber (22) in the first operating area during the respective introduction process carried out within the respective work cycle. [4] Method for operating an internal combustion engine (10) of a motor vehicle, in which the internal combustion engine (10) has at least one combustion chamber (22), an injection element (24) associated with the combustion chamber (22) by means of which a fuel can be introduced into the combustion chamber (22), and a pre-chamber spark plug (28) associated with the combustion chamber (22), which has a pre-chamber (30) fluidically connected to the combustion chamber (22) via several openings (32), into which at least a part of a fuel-air mixture comprising fuel and air can be introduced from the combustion chamber (22) via the openings (32), characterized by , that: - in a first operating range of the internal combustion engine (10), which in the first operating range is operated with at least one first load and at least one first speed, at least or exactly two successive and temporally spaced injection processes are carried out within a respective working cycle of the internal combustion engine (10), in which by means of the injection element (24) exactly one respective quantity of fuel is introduced into the combustion chamber (22); - in a second operating range of the internal combustion engine (10), which in the second operating range is operated with at least a second load higher than the first load and / or with a second speed higher than the first speed, at least or exactly two successive and temporally spaced injection processes are carried out within a respective working cycle of the internal combustion engine (10), in which exactly a respective quantity of fuel is introduced into the combustion chamber (22) by means of the injection element (24); and - to cool at least a part of the pre-chamber spark plug (28), the respective last insertion process within the respective working cycle is carried out later in the second operating range than in the first operating range within the respective working cycle. [5] Method according to claim 4, characterized by, that the sum of the quantities introduced into the combustion chamber (22) in the second operating area in the respective introduction processes carried out within the respective work cycle differs from the sum of the quantities introduced into the combustion chamber (22) in the first operating area in the respective introduction processes carried out within the respective work cycle. [6] Method according to claim 5, characterized by , that the sum of the quantities introduced into the combustion chamber (22) in the second operating area in the respective introduction operations carried out within the respective work cycle is greater than the sum of the quantities introduced into the combustion chamber (22) in the first operating area in the respective introduction operations carried out within the respective work cycle. [7] Method according to any one of claims 4 to 6, characterized by, that in the second operating area, a first of the injection operations carried out within the respective work cycle is carried out before a second of the injection operations carried out within the respective work cycle, wherein the quantity introduced into the combustion chamber in the respective second injection operation is in a range of 1% to 20% inclusive, in particular in a range of 3% to 10% inclusive, of the quantity introduced into the combustion chamber in the respective first injection operation. [8] Method according to any one of the preceding claims, characterized by , that the openings (32) cause a tumble-shaped flow of the fuel-air mixture flowing into the pre-chamber (30) via the openings (32).

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