Method for water injection into a combustion engine having an exhaust gas recirculation system

Abstract

A method for injecting water into a combustion engine with an exhaust gas recirculation system, the combustion engine having at least the following components: a combustion chamber; an air passage; a fuel input unit; a water injection nozzle; and an exhaust gas line with an exhaust gas recirculation system, by means of which an exhaust gas volume flow with an exhaust gas temperature can be supplied to the combustion chamber in a regulated manner from the exhaust gas, the exhaust gas recirculation system comprising a cooler for regulating the exhaust gas temperature of the returned exhaust gas volume flow, providing the combustion chamber with a combustion chamber mixture with a fresh intake air temperature, the combustion chamber mixture comprising, according to regulations, a provided air volume flow, a fuel, an exhaust gas volume flow and a water component, the method comprising at least the following steps: a. determining the water component required for the combustion chamber mixture in order to achieve a desired fresh intake air temperature; and b. adjusting the exhaust gas volume flow and / or the exhaust gas temperature in order to evaporate the water component determined in step a.

Description

Technical Field

[0001] The invention relates to a method for water injection into a combustion engine having an exhaust gas recirculation system, wherein

[0002] The combustion engine has at least the following components:

[0003] - Combustion chamber;

[0004] - air passages;

[0005] - fuel input unit;

[0006] - water injection nozzles; and

[0007] - Exhaust gas line with exhaust gas recirculation system,

[0008] wherein an exhaust gas volume flow at the exhaust gas temperature can be supplied from the exhaust gas to the combustion chamber in a regulated manner by means of the exhaust gas recirculation system,

[0009] The exhaust gas recirculation system comprises a cooler for regulating the exhaust gas temperature of the recirculated exhaust gas volume flow, and

[0010] wherein a combustion chamber mixture having a fresh intake temperature is supplied to the combustion chamber, the combustion chamber mixture comprising a provided air volume flow, a fuel, an exhaust gas volume flow and a water component as specified, and

[0011] The method comprises at least the following steps:

[0012] a. determining the water component required for the combustion chamber mixture in order to achieve the desired fresh intake air temperature; and

[0013] b. Adjusting the exhaust gas volume flow and / or the exhaust gas temperature in order to evaporate the water component determined in step a. The invention also relates to a combustion engine with an exhaust gas recirculation system and to a motor vehicle. Background Art

[0014] Combustion engines are known from the prior art, for example for driving motor vehicles. It is desirable for combustion engines to operate as efficiently as possible in all operating states, but at the same time with low fuel consumption and low pollutant emissions and with maximum stability and durability. In particular, when the air-fuel mixture in the combustion chamber is lean, reduced pollutant emissions can be achieved with the help of exhaust gas recirculation systems. Here, a certain proportion of exhaust gas is supplied to the fresh air in a regulated manner for the fresh intake of the combustion chamber. Exhaust gas recirculation systems are known, which operate at low pressure (after the exhaust gas turbine) and / or at high pressure (in front of the exhaust gas turbine). The corresponding recirculation circuit includes a (corresponding low-pressure or high-pressure) cooler, by means of which the recirculated proportion of exhaust gas can be cooled to a temperature of, for example, 30° C. [thirty degrees Celsius] to 150° C. or 80° C. to 200° C., and then this proportion of exhaust gas is added to the air volume flow. Preferably, at least one catalytic converter and / or a particle filter is connected upstream of one or more coolers in the exhaust gas recirculation system.

[0015] In combustion engines, malfunctions of the combustion engine (e.g., a tendency to knock) can occur in the high power range due to excessively high fresh intake air temperatures, which results in a reduction in the efficiency of the combustion engine. To solve this problem, it is now common to supply water in the form of a fine spray to the fresh intake air, so that a significant reduction in the fresh intake air temperature can be achieved due to evaporation. It has been found that a considerable proportion of water is introduced into the combustion chamber in an unevaporated state. This water can lead to interference with the combustion process in the combustion chamber, primarily due to dilution of the engine lubricant, or even to mechanical damage. Summary of the invention

[0016] Starting from this, the object on which the present invention is based is to at least partially overcome the disadvantages known from the prior art. The features according to the invention are derived from the independent claims, and their advantageous embodiments are shown in the dependent claims. The features of the claims can be combined in any technically reasonable manner, wherein for this purpose, the explanations from the following description and the features from the drawings can also be used, which include supplementary embodiments of the invention.

[0017] The invention relates to a method for injecting water into a combustion engine having an exhaust gas recirculation system, wherein

[0018] The combustion engine has at least the following components:

[0019] - a combustion chamber having an inlet and an outlet;

[0020] an air channel, by means of which an air volume flow having an air temperature is provided via an inlet of the combustion chamber;

[0021] - a fuel input unit for adding fuel to the combustion chamber in a regulated manner;

[0022] a water injection nozzle, by means of which the combustion chamber can be supplied with a water component; and

[0023] an exhaust gas line with an exhaust gas recirculation system, which exhaust gas line conducts the exhaust gas via an outlet of the combustion chamber,

[0024] wherein an exhaust gas volume flow at the exhaust gas temperature can be supplied from the exhaust gas to the combustion chamber in a regulated manner by means of the exhaust gas recirculation system,

[0025] The exhaust gas recirculation system comprises a cooler for regulating the exhaust gas temperature of the recirculated exhaust gas volume flow, and

[0026] In this case, a combustion chamber mixture having a fresh intake temperature is supplied to the combustion chamber, which, in addition to the air volume flow, comprises the elements which can be supplied in a defined amount:

[0027] -fuel,

[0028] - exhaust gas volume flow, and

[0029] - water component,

[0030] And wherein the method comprises at least the following steps:

[0031] a. determining the water component required for the combustion chamber mixture in order to achieve the desired fresh intake air temperature; and

[0032] b. Adjusting the exhaust gas volume flow and / or the exhaust gas temperature in order to evaporate the water component determined in step a.

[0033] In the following, if an axial direction, a radial direction or a circumferential direction and the corresponding terms are used without explicit indication otherwise, reference is made to the mentioned axis of rotation. Unless explicitly stated to the contrary, the ordinal numbers used in the preceding and following description are only for clear distinction and do not reflect any order or ranking of the components referred to. An ordinal number greater than one does not necessarily mean that another such component must be present.

[0034] With the method proposed here, the water component required for avoiding knocking can be evaporated more efficiently by adapting the exhaust gas volume flow or the exhaust gas temperature to the determined water component. Basically, the fresh intake air temperature is a function of the air volume flow, the air temperature, the exhaust gas volume flow, the exhaust gas temperature and the water component. The fresh intake air temperature should be adjusted for optimal combustion in the combustion chamber (usually predictively and based on a characteristic map or model). In this method, the goal of a low fresh intake air temperature is maintained.

[0035] However, it is known that under given conditions (temperature and residence time) evaporation of water often only takes place inadequately. This is due to the fact that the water (droplets) have significantly higher surface stresses than the (liquid) fuel (droplets). This results in interference with the combustion process in the combustion chamber, which in turn impairs the efficiency of the combustion engine and thus the CO2 emissions, and / or deposits of liquid water on the walls of the combustion chamber occur.

[0036] The method proposed here can be implemented, for example, with conventional combustion engines, such as reciprocating piston engines, in which the fuel is expansively burned in the combustion chamber by means of an ignition unit (gasoline principle) or by self-ignition (diesel principle). Air volume flow and fuel are necessary for a combustible mixture, and exhaust gas recirculation is necessary for the desired low pollutant emissions (in the case of a lean combustion chamber mixture). As described at the outset, it is generally known to add a water component to the combustion chamber in order to avoid knocking (i.e. uncontrolled combustion due to often audible pressure peaks).

[0037] The method proposed here can be implemented not only on combustion engines that work on the suction principle, but also in combustion engines with direct fuel injection. Since the exhaust gas temperature of the exhaust gas volume flow that is guided back is usually too high to be supplied to the combustion chamber without treatment, a cooler is provided in the exhaust gas recirculation system, by means of which the exhaust gas temperature can be adjusted. The cooler works, for example, as a heat exchanger, wherein the coolant is usually cooled by forced convection, i.e., in motor vehicles, it is usually cooled depending on the vehicle speed. For example, when driving on a mountain road, such a cooler reaches its power limit due to the reduced air flow speed and at the same time due to the high torque required by the combustion engine. Therefore, in the case of the exhaust gas volume flow required to comply with the preset exhaust gas characteristic value, it is necessary to further increase the water component. In this case, it should be pointed out that the method can not only be used for driving on mountain roads, but also has the additional advantage that the knock tendency of the combustion engine can also be effectively suppressed in this state.

[0038] In contrast to known methods, it is proposed here to determine the water content of the combustion chamber mixture required in order to achieve a desired fresh intake air temperature. The temperature of the combustion chamber mixture in the combustion chamber is reduced in this way using this water content until a knock tendency in operation according to the prediction is eliminated. The exhaust gas volume flow and / or the exhaust gas temperature are now adjusted solely on the basis of the determined water content. In this case, a higher exhaust gas temperature and / or a greater exhaust gas volume flow are regularly generated, so that the water content evaporates more efficiently. According to the prediction, the water content is completely evaporated.

[0039] Furthermore, in an advantageous embodiment of the method it is provided that in step b. the exhaust gas temperature is increased and the exhaust gas volume flow is reduced with increasing water content.

[0040] In this particular embodiment, a high exhaust gas temperature and a low exhaust gas volume flow are set in the case of a large water component, so that the water component can be evaporated efficiently from the high exhaust gas temperature. At the same time, the desired fresh intake air temperature can be achieved with a reduced exhaust gas volume flow (together with the air temperature and the determined water component). It is advantageous here that the cooler can be operated at a reduced power at an operating point, for example, within the range of its upper power limit; because on the one hand (compared to a larger exhaust gas volume flow and a lower exhaust gas temperature), a reduced cooling power is required due to the increased exhaust gas temperature, and on the other hand, a reduced cooling power is required due to the reduced exhaust gas volume flow. Therefore, in an advantageous embodiment, a cooler with a smaller upper power limit compared to the prior art can be used. Alternatively or additionally, a larger amount of exhaust gas can be recirculated, because the cooler can be operated more frequently or more reliably within its power spectrum.

[0041] Furthermore, in an advantageous embodiment of the method it is provided that the exhaust gas recirculation system has a first exhaust gas line with a first cooler and / or a second exhaust gas line with a second cooler, so that the first exhaust gas temperature is regulated with the first cooler and the second exhaust gas temperature is regulated with the second cooler.

[0042] wherein the first cooler can be operated at a high pressure and the second cooler can be operated at a low pressure,

[0043] In this case, the cooler preferably regulates the respective exhaust gas temperature only at its adjustable cooling capacity.

[0044] Here, three variants of an exhaust gas recirculation system are proposed, in a first variant, only a first exhaust gas line with a first cooler is provided, which can be operated in a high-pressure system, that is, arranged upstream of the turbine of a turbocharger of a combustion engine. The (associated) first exhaust gas temperature of this exhaust gas volume flow is, for example, between about 80° C. [eighty degrees Celsius] and about 200° C. In a second variant, only a second exhaust gas line with a second cooler is provided, which can be operated in a low-pressure system and is therefore arranged downstream of the turbine of a turbocharger of a combustion engine. The (associated) second exhaust gas temperature of this exhaust gas volume flow is, for example, between about 30° C. [thirty degrees Celsius] and about 150° C. Therefore (in the case of a regular air supply from the environment), the mixture of the exhaust gas volume flow and the air volume flow has a mixture temperature that is higher than the air temperature. In a third variant of the exhaust gas recirculation system, a high-pressure exhaust gas line and a low-pressure exhaust gas line are provided, wherein preferably each of these is equipped with a cooler. In this case, it should be pointed out that the exhaust gas aftertreatment device is preferably connected upstream of the cooler, for example by means of a catalytic converter and / or a particle filter, very particularly preferably by means of a four-way catalytic converter in which the function of a particle filter is integrated. It should also be pointed out that the method proposed here is significantly simpler in terms of the adjustability of the low-pressure exhaust gas line. This is especially due to the fact that the adjustment variables and / or adjustment times are more moderate due to the lower pressure. In contrast, the adjustability through the high-pressure exhaust gas line is better in terms of short distances, because the dead time element is therefore smaller, and neither the turbine nor the turbocharger (compressor) is included as a disturbance variable in the control route. In a preferred embodiment with a third variant in which a high-pressure exhaust gas line and a low-pressure exhaust gas line are present, the method is preferably implemented only with the aid of a first cooler, i.e. a high-pressure cooler.

[0045] In a preferred embodiment, the exhaust gas temperature is regulated only at the cooling capacity of the corresponding cooler. The exhaust gas temperature referred to here is the temperature that is present after the corresponding cooler or shortly before encountering the added water component. The outlet temperature of the combustion chamber depends on the full load of the combustion engine and the operating state of the combustion engine and is regulated to the desired exhaust gas temperature by means of the cooling capacity of the relevant cooler. The outlet temperature of the exhaust gas introduced into the corresponding exhaust gas line is therefore an input variable or disturbance variable of this partial control system.

[0046] Furthermore, in an advantageous embodiment of the method, it is provided that the exhaust gas recirculation system has at least one valve,

[0047] In this case, the corresponding exhaust gas volume flow is regulated by means of the valve.

[0048] In this embodiment, at least one valve is provided, preferably one valve per exhaust gas line, by means of which the exhaust gas volume flow is regulated. It should also be noted here that the exhaust gas volume flow is the exhaust gas volume flow which is present downstream of the respective cooler or when a water component is added. Although the escape volume flow (per stroke) leaving the combustion chamber depends on the load state (requested torque and therefore operating pressure), due to the very different escape temperatures which are load-dependent and state-dependent, the exhaust gas volume flow can be associated with very different opening times of the respective valves (even in the case of a desired constant exhaust gas volume flow).

[0049] Furthermore, in an advantageous embodiment of the method it is provided that the water component is injected directly into:

[0050] - Combustion chamber;

[0051] a collector which is arranged upstream of the inlet of the combustion chamber and in which the air volume flow and the exhaust gas volume flow are introduced; and / or

[0052] In the exhaust gas recirculation system downstream of the cooler and before the exhaust gas volume flow is combined with the air volume flow.

[0053] Here, three particularly preferred variants are proposed, wherein other variants can also be implemented. The places different from the places mentioned here represent the intermediate states of the variants mentioned here. In the first variant, the water component is directly injected into the combustion chamber, so that the evaporation enthalpy can be used in the combustion process in the combustion chamber, and the reaction time can be the shortest. In the second variant, the water component is directly input into the collector, which corresponds to the carburetor or is connected upstream or downstream of the carburetor in a combustion engine with an suction principle, for example. This variant is particularly simple in terms of the design of the equipment and in terms of the regulation of the method, and still always has a very short response time. In the third variant, the water component is added to the exhaust gas volume flow as early as possible, for example, immediately when escaping from the corresponding cooler, so that on the one hand, the residence time of the added water component is particularly long, and on the other hand, the exhaust gas temperature, which is usually higher than the air temperature, realizes a particularly complete evaporation.

[0054] According to a further aspect, a combustion engine with an exhaust gas recirculation system is proposed, which is used to carry out a method according to the above-described embodiment, wherein

[0055] The combustion engine has at least the following components:

[0056] - at least one reciprocating cylinder having a working surface and a combustion chamber with an inlet and an outlet;

[0057] - the same number of reciprocating pistons as reciprocating cylinders, which perform a stroke movement in the combustion chamber in the axial direction of the cylinder, guided by corresponding working surfaces;

[0058] a crankshaft having a torque shaft, to which the at least one reciprocating piston is connected in a force-transmitting manner for converting an axial cylinder movement of the at least one reciprocating piston into a rotation of the crankshaft about the torque shaft;

[0059] an air channel, by means of which an air volume flow is provided via an inlet of the combustion chamber;

[0060] - a fuel input unit for adding fuel to the combustion chamber in a regulated manner;

[0061] a water injection nozzle, by means of which the combustion chamber can be supplied with a water component; and

[0062] an exhaust gas line with an exhaust gas recirculation system, which exhaust gas line conducts the exhaust gas via an outlet of the combustion chamber,

[0063] wherein an exhaust gas volume flow can be supplied from the exhaust gas to the combustion chamber in a regulated manner by means of the exhaust gas recirculation system,

[0064] The exhaust gas recirculation system comprises a cooler for regulating the exhaust gas temperature of the recirculated exhaust gas volume flow.

[0065] The combustion engine proposed here is a reciprocating piston engine, in which one or more combustion chambers are provided, wherein the reciprocating piston is forced to perform a stroke movement in a reciprocating cylinder by means of ignition of the combustion chamber mixture, wherein the reciprocating piston is guided by a working surface. This axial movement is converted into a rotational movement by means of a crankshaft, and thus a torque is output about the torque axis of the combustion engine. The combustion engine is, for example, an engine running on gasoline (petrol engine) or a diesel engine, or alternatively a reciprocating piston engine running on gas or hydrogen. For example, the method is implemented by a conventional engine control device, and / or the measured values ​​are detected by conventional sensors. The combustion engine is, for example, implemented conventionally, wherein preferably conventional corresponding regulating sensors and measuring devices are already provided in order to implement the above method.

[0066] With the method proposed here, a combustion engine can be operated without impairing the combustion process and lubrication in the combustion chamber, for example without adding water to the oil sump and / or diluting the lubricant in the rolling bearings, and at the same time effectively suppressing knock tendencies.

[0067] According to another aspect, a motor vehicle is proposed, the motor vehicle having:

[0068] According to the combustion engine and at least one propulsion wheel according to the embodiment described above,

[0069] Therein, a combustion engine for propelling the motor vehicle is connected to the at least one propulsion wheel in a torque-transmitting manner.

[0070] The combustion engine proposed here is configured in the embodiment proposed here for propelling a motor vehicle. The motor vehicle is shown here only incompletely with its components and is, for example, designed conventionally in other respects. The propulsion wheels are, for example, two wheels of a common axle, for example the rear axle of a four-wheeled motor vehicle, and are connected to the combustion engine in a torque-transmitting manner, preferably detachably, by means of a drive train.

[0071] With the method proposed here, a combustion engine of a motor vehicle can be operated without impairing the combustion process and lubrication in the combustion chamber, for example without adding water to the oil sump and / or diluting the lubricant in the rolling bearings, and at the same time effectively suppressing knock tendencies. BRIEF DESCRIPTION OF THE DRAWINGS

[0072] The invention is described in detail below, starting from the relevant technical background and with reference to the relevant drawings showing preferred designs. The invention is not limited in any way by the purely schematic drawings, wherein it should be noted that these drawings are not accurate in size and are not suitable for defining dimensional ratios. In the drawings:

[0073] Figure 1 : shows a water injected combustion engine; and

[0074] Figure 2 : A motor vehicle having a combustion engine is shown. DETAILED DESCRIPTION

[0075] exist Figure 1Schematically shows a combustion engine 1 in which the above-described method for water injection can be implemented. In this embodiment, the combustion engine 1 comprises a plurality of (for example six) reciprocating cylinders 18 and a corresponding number of reciprocating pistons 20, which are guided axially (here vertically in the schematic diagram) by corresponding working surfaces 19, so that during the stroke movement 21, the combustion chamber 3 (as part of the corresponding reciprocating cylinder 18) is compressed and expanded. The reciprocating pistons 20 are connected to a common crankshaft 22, so that due to the stroke movement 21, a torque can be generated about a torque axis 23. The components and features of the corresponding functional components of the reciprocating cylinder 18 are here respectively provided with reference numerals only once and for the whole. The combustion chamber 3 has an inlet 4, which is connected to the air channel 6 and the exhaust gas recirculation system 2 for supplying at least so-called fresh air. In addition, the combustion chamber 3 has an outlet 5, which is connected to the exhaust gas line 9 (via an elbow 27). In the embodiment, a spark plug (petrol engine) or a glow plug (diesel engine) is also provided. The combustion chamber 3 is supplied with a (possibly pressurized) combustion chamber mixture 12 via the inlet 4. Supply is also understood to mean suction. In this embodiment, a collector 17 is connected upstream of the inlet 4, wherein a fuel supply unit 7 is optionally provided there, i.e. the collector 17 is designed as a carburetor. Alternatively, a fuel injection nozzle is provided in each combustion chamber 3.

[0076] A first (high-pressure) exhaust gas line 13 branches off from the exhaust gas line 9, in which a corresponding adjustable first valve 15 is arranged, so that the (high-pressure) exhaust gas volume flow can be adjusted (for example, in a time-controlled and / or pressure-controlled manner). In addition, a second (low-pressure) exhaust gas line 14 branches off from the exhaust gas line 9, in which a corresponding adjustable second valve 16 is arranged, so that the (low-pressure) exhaust gas volume flow can be adjusted (for example, in a time-controlled and / or pressure-controlled manner). The first (high-pressure) exhaust gas line 13 branches off upstream of the turbine 28, while the second (low-pressure) exhaust gas line 14 branches off downstream of the turbine 28. Accordingly, the first (high-pressure) exhaust gas volume flow is introduced into the air channel 6 downstream of the compressor 29, while the second (low-pressure) exhaust gas volume flow is introduced into the air channel 6 upstream of the compressor 29. A first (high-pressure) cooler 10 is provided in the first (high-pressure) exhaust gas line 13, and a second (low-pressure) cooler 11 is provided in the second (low-pressure) exhaust gas line 14, wherein preferably the cooling capacity of at least one of the two coolers 10, 11 is adjustable. Alternatively, only a single exhaust gas line is provided or can be adjusted accordingly.

[0077] Here, three possible locations for the water injection nozzle 8 are shown, wherein these locations are preferably alternative to each other. One variant shows the injection of water directly into the combustion chamber 3, so that the combustion chamber mixture 12 is only formed in the combustion chamber 3 itself. This enables a rapid reaction to changes in the load and / or operating state of the combustion engine 1. The variant shown by the short dashed line shows the water injection nozzle 8 directly into the collector 17, so that the combustion chamber mixture 12 (or the premix without fuel) is already formed outside the combustion chamber 3 and the residence time of the water component in the fresh air is long. The variant shown by the long dashed line shows the water injection nozzle 8 immediately after the (first) cooler 10, so that on the one hand, the water component already meets the relatively hot exhaust gas and also has a long residence time in the fresh air.

[0078] Figure 2 A motor vehicle 24 with a combustion engine 1 is shown in a top view. The combustion engine 1, which is arranged in the rear part of the four-wheeled motor vehicle 24, is connected with its torque shaft 23 to the left and right propulsion wheels 25 and 26 (here on a common axle) in a torque-transmitting manner via a differential 30. During operation of the combustion engine 1, knocking tendencies that are dependent on the operating point are suppressed by means of water injection.

[0079] The method for water injection proposed here makes it possible to achieve efficient and reliable evaporation of the injected water component.

[0080] List of Reference Numerals

[0081] 1 Combustion engine

[0082] 2 Exhaust Gas Recirculation System

[0083] 3 Combustion chamber

[0084] 4 Entrance

[0085] 5. Exit

[0086] 6 Air channels

[0087] 7 Fuel input unit

[0088] 8 Water injection nozzle

[0089] 9 Exhaust line

[0090] 10 High pressure cooler

[0091] 11 Low pressure cooler

[0092] 12 Combustion chamber mixture

[0093] 13 High-pressure exhaust gas line

[0094] 14 Low-pressure exhaust gas line

[0095] 15 First valve

[0096] 16 Second valve

[0097] 17 Collector

[0098] 18 Reciprocating Cylinder

[0099] 19 Working surface

[0100] 20 Reciprocating Piston

[0101] 21 stroke motion

[0102] 22 Crankshaft

[0103] 23 Torque shaft

[0104] 24 Motor Vehicles

[0105] 25 Left propel wheel

[0106] 26 Right propel wheel

[0107] 27 Elbow

[0108] 28 Turbine

[0109] 29 Compressor

[0110] 30 Differential

Claims

1. A method for injecting water into a combustion engine (1) having an exhaust gas recirculation system (2), wherein The combustion engine (1) has at least the following components: - a combustion chamber (3) having an inlet (4) and an outlet (5); an air duct (6), by means of which an air volume flow at an air temperature is provided via the inlet (4) of the combustion chamber (3); - a fuel input unit (7) for adding fuel to the combustion chamber (3) in a regulated manner; a water injection nozzle (8), by means of which a water component can be supplied to the combustion chamber (3); as well as an exhaust gas line (9) with an exhaust gas recirculation system (2), which exhaust gas line conducts the exhaust gas via the outlet (5) of the combustion chamber (3), wherein an exhaust gas volume flow at the exhaust gas temperature can be supplied from the exhaust gas to the combustion chamber (3) in a regulated manner by means of the exhaust gas recirculation system (2), The exhaust gas recirculation system (2) comprises a cooler for regulating the exhaust gas temperature of the recirculated exhaust gas volume flow, and The combustion chamber (3) is supplied with a combustion chamber mixture (12) having a fresh intake temperature, which, in addition to the air volume flow, comprises the following elements which can be supplied in predetermined quantities: -fuel, - exhaust gas volume flow, and - water component, And wherein the method comprises at least the following steps: a. determining the water component of the combustion chamber mixture (12) required to achieve the desired fresh intake air temperature; and b. adjusting the exhaust gas volume flow rate and / or the exhaust gas temperature to evaporate the water component determined in step a.; The exhaust gas recirculation system (2) has at least one valve (15, 16), wherein the respective exhaust gas volume flow is adjusted by means of the valve (15, 16).

2. The method according to claim 1, wherein In step b., the exhaust gas temperature is increased and the exhaust gas volume flow is reduced with increasing water content.

3. The method according to claim 1 or claim 2, wherein The cooler comprises a first cooler (10) and / or a second cooler (11); The exhaust gas recirculation system (2) comprises a first exhaust gas line (13) with the first cooler (10) and / or a second exhaust gas line (14) with the second cooler (11), so that the first exhaust gas temperature is adjusted by means of the first cooler (10) and the second exhaust gas temperature is adjusted by means of the second cooler (11). The first cooler (10) can be operated at a high pressure, and the second cooler (11) can be operated at a low pressure.

4. The method according to claim 3, wherein The cooler merely regulates the corresponding exhaust gas temperature at its adjustable cooling capacity.

5. The method according to claim 1 or claim 2, wherein Inject the water component directly into: - a combustion chamber (3); a collector (17) which is arranged upstream of the inlet (4) of the combustion chamber (3) and into which the air volume flow and the exhaust gas volume flow are introduced; and / or - in the exhaust gas recirculation system (2) downstream of the cooler and before the exhaust gas volume flow is combined with the air volume flow.

6. A combustion engine (1) with an exhaust gas recirculation system (2) for carrying out the method according to any one of the preceding claims, The combustion engine (1) has at least the following components: - at least one reciprocating cylinder (18) having a working surface (19) and a combustion chamber (3) with an inlet (4) and an outlet (5); - a number of reciprocating pistons (20) equal to the number of reciprocating cylinders (18), which perform a cylinder axial stroke movement (21) in the combustion chamber (3) guided by corresponding working surfaces (19); - a crankshaft (22) having a torque shaft (23), to which the at least one reciprocating piston (20) is connected in a force-transmitting manner, for converting the cylinder axial movement of the at least one reciprocating piston into a rotation of the crankshaft (22) about the torque shaft (23); an air channel (6), by means of which an air volume flow is provided via the inlet (4) of the combustion chamber (3); - a fuel input unit (7) for adding fuel to the combustion chamber (3) in a regulated manner; a water injection nozzle (8), by means of which a water component can be supplied to the combustion chamber (3); as well as an exhaust gas line (9) with an exhaust gas recirculation system (2), which exhaust gas line conducts the exhaust gas via the outlet (5) of the combustion chamber (3), wherein an exhaust gas volume flow can be supplied from the exhaust gas to the combustion chamber (3) in a regulated manner by means of the exhaust gas recirculation system (2), The exhaust gas recirculation system (2) comprises a cooler for regulating the exhaust gas temperature of the recirculated exhaust gas volume flow.

7. A motor vehicle (24) having A combustion engine (1) according to claim 6 and at least one propulsion wheel (25, 26), A combustion engine (1) for propelling the motor vehicle (24) is connected to the at least one propulsion wheel (25, 26) in a torque-transmitting manner.

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