Method for operating an internal combustion engine for a motor vehicle, and internal combustion engine

Abstract

The invention relates to a method for operating an internal combustion engine (1) for a motor vehicle, in which the internal combustion engine (1) has at least one combustion chamber (2), at least one fuel injection device (8) for injecting fuel into the combustion chamber (2), an exhaust gas section (9) through which an exhaust gas can flow, and at least one secondary air line (12) through which secondary air can flow and which is fluidically connected to the exhaust gas section (9) at an introduction point (14), wherein the internal combustion engine (1) is operated in a drying operating mode (26) in which the secondary air is introduced into the exhaust gas section (9) at the introduction point (14) via the secondary air line (12) and the internal combustion engine (1) is in overrun mode (27) in which the fuel is not injected into the combustion chamber (2) and no combustion operations take place in the combustion chamber (2), or the internal combustion engine (1) is in fired overrun mode (28) in which fuel is injected into the combustion chamber (2) and the combustion operations take place in the combustion chamber (2).

Description

[0001] Method for operating an internal combustion engine for a motor vehicle and internal combustion engine

[0002] The invention relates to a method for operating an internal combustion engine for a motor vehicle according to the preamble of patent claim 1. Furthermore, the invention relates to an internal combustion engine for a motor vehicle which is designed to carry out such a method.

[0003] DE 102020 007 000 A1 discloses an internal combustion engine for a motor vehicle, having an exhaust tract through which exhaust gas from at least one combustion chamber of the internal combustion engine can flow, and having a secondary air line through which secondary air can flow, by means of which the secondary air flowing through the secondary air line can be introduced into the exhaust tract.

[0004] The object of the present invention is to provide a method for operating an internal combustion engine for a motor vehicle and such an internal combustion engine, so that a secondary air system of the internal combustion engine can be operated particularly reliably.

[0005] This object is achieved according to the invention by a method for operating an internal combustion engine for a motor vehicle having the features of patent claim 1 and by an internal combustion engine for a motor vehicle having the features of patent claim 10. Advantageous embodiments with expedient further developments of the invention are specified in the remaining claims.

[0006] A first aspect of the invention relates to a method for operating an internal combustion engine for a motor vehicle, which is designed, for example, as a motor vehicle, in particular as a passenger car or as a commercial vehicle. Preferably, the motor vehicle can be driven by means of the internal combustion engine. Preferably, the internal combustion engine has an output shaft, which is rotatable, in particular, about a shaft axis of rotation, via which the motor vehicle can be driven or is driven. The internal combustion engine preferably has at least one combustion chamber, which is designed, for example, as a cylinder. The combustion chamber is, for example, at least partially delimited by at least one housing element, which is designed, for example, as a cylinder wall, and is formed, in particular, at least in regions, by an engine block.For example, combustion processes take place in the combustion chamber in which a fuel-air mixture is burned, resulting in exhaust gases from the internal combustion engine.

[0007] The internal combustion engine, for example, has at least one intake tract through which air can flow, through which air can be supplied to the combustion chamber. Thus, the air can be introduced into the combustion chamber, in particular directly, via the intake tract.

[0008] For example, the combustion chamber is partially delimited by a piston element, which can in particular be referred to as a piston. The piston element is preferably mounted so as to be movable, in particular translationally, relative to the housing element. For example, the internal combustion engine has a crankshaft which is rotatable about a crankshaft axis of rotation and which is coupled, in particular mechanically, to the piston element. Preferably, there is at least one connecting rod by means of which a transitory movement of the piston element can be or is converted into a rotational movement of the crankshaft. Thus, the crankshaft can be driven by the piston element via the connecting rod and can therefore be rotated, in particular, about its crankshaft axis of rotation.

[0009] The internal combustion engine has at least one fuel introduction device for introducing, in particular for injecting, fuel into the combustion chamber. The fuel introduction device is designed, for example, as a fuel injection device, in particular as an injector. For example, the fuel can be introduced, in particular injected, directly into the combustion chamber via the fuel introduction device or by means of the fuel introduction device, or the fuel can be introduced, in particular injected, directly into the intake tract and thus introduced into the combustion chamber via the intake tract, i.e. via the intake tract. The internal combustion engine has at least one exhaust tract through which the exhaust gas from the combustion chamber of the internal combustion engine flows. The exhaust gas can be discharged from the combustion chamber via the exhaust tract.

[0010] The internal combustion engine has at least one secondary air line through which secondary air can flow, which is, for example, part of a secondary air system of the internal combustion engine. The secondary air system can thus have the secondary air line. The secondary air line is or can be fluidly connected to the exhaust tract at at least one inlet point, in particular directly, whereby the secondary air flowing through the secondary air line can be introduced, in particular blown, into the exhaust tract via the secondary air line at the inlet point or via the inlet point, in particular directly. The introduction of the secondary air into the exhaust tract can therefore be referred to in particular as secondary air injection. The secondary air line can in particular be referred to as a secondary air duct.

[0011] For example, in particular in a heating mode of the internal combustion engine, the secondary air is introduced into the exhaust tract, in particular directly, at the inlet point via the secondary air line in order to burn unburned and combustible fuel components contained in the exhaust gas, which, for example, originate from the combustion chamber and have passed unburned from the combustion chamber into the exhaust tract. As a result, for example, an exhaust gas aftertreatment device arranged in the exhaust tract for aftertreating the exhaust gas can be heated effectively and quickly, thereby ensuring particularly low-emission operation of the internal combustion engine. In other words, for example, in particular in heating mode, the exhaust gas aftertreatment device is acted upon by means of the secondary air introduced into the exhaust tract via the secondary air line at the inlet point in order to heat the exhaust gas aftertreatment device, in particular through post-oxidation.The secondary air can thus be introduced at the inlet point into at least one line element of the exhaust tract, wherein this line element leads, for example, to the exhaust gas aftertreatment device and / or to an outlet of the exhaust tract, particularly referred to as an exhaust. The exhaust gas aftertreatment device can be understood, in particular, as a cleaning device by means of which the exhaust gas can be cleaned. The exhaust gas aftertreatment device is designed, for example, as a catalytic converter. For example, after or during a cold start, the internal combustion engine is operated in the heating mode, i.e., with secondary air injection. In the heating mode, for example, the introduction of the fuel via the fuel introduction device and the combustion processes in the combustion chamber take place.This means that, for example, in heating mode, the fuel is introduced into the combustion chamber via the fuel introduction device and in heating mode, the fuel-air mixture is burned in the combustion chamber.

[0012] The introduction of secondary air, in particular secondary air injection, means that the secondary air is introduced or injected into the exhaust system via the secondary air line at the inlet point, in particular bypassing or avoiding the combustion chamber. Thus, the secondary air bypasses, for example, all combustion chambers of the internal combustion engine and therefore does not originate from the combustion chamber.

[0013] In order to be able to operate the secondary air system particularly reliably, i.e. to particularly increase the reliability of the secondary air system and, in particular, to be able to particularly increase security against icing of the secondary air system, the invention provides that the internal combustion engine is operated in a drying operating mode, which is different from the heating operating mode, in particular for removing condensate and / or moisture from the secondary air system, for example from the secondary air line, in which drying operating mode the secondary air flowing through the secondary air is introduced via the secondary air line at the inlet point, in particular directly, into the exhaust tract. In other words, the introduction, in particular the blowing in, of the secondary air takes place in the drying operating mode.This means in particular that the internal combustion engine is operated in the drying mode with secondary air injection.

[0014] It is provided that in the drying operating mode the internal combustion engine is in overrun mode in which the introduction of fuel, in particular via the fuel introduction device, into the combustion chamber is omitted. This means that in overrun mode the fuel is not introduced into the combustion chamber, i.e. the introduction, in particular injection, of the fuel is switched off or will be switched off in the overrun mode. In overrun mode no combustion processes take place in the combustion chamber. This means that the fuel-air mixture or no fuel-air mixture is burned in the combustion chamber in the overrun mode, as a result of which in particular no exhaust gas is generated in the overrun mode. Overrun mode can be understood in particular as an engine overrun phase.For example, in overrun mode, the air flowing through the intake tract is introduced or conveyed through the combustion chamber into the exhaust tract. For example, in overrun mode, the output shaft is stationary, meaning that the motor vehicle is preferably not driven, particularly via the output shaft, during overrun mode. This means that in overrun mode, the motor vehicle is preferably not driven by the internal combustion engine.

[0015] Alternatively or additionally, it is provided that the internal combustion engine is in a fired overrun mode in the drying operating mode, in particular one that is different from the overrun mode. In other words, the internal combustion engine is operated in fired overrun mode in the drying operating mode. In fired overrun mode, fuel is introduced into the combustion chamber via the introduction device or by means of the introduction device. This means that in fired overrun mode, the fuel is introduced into the combustion chamber, in particular via the introduction device, so that the injection is not switched off or is switched off, for example. In fired overrun mode, combustion processes take place in the combustion chamber.This means that in the fired overrun mode, the fuel-air mixture is combusted in the combustion chamber, resulting in, in particular, the exhaust gas of the internal combustion engine in the fired overrun mode. Preferably, the output shaft is stationary in the fired overrun mode, whereby the motor vehicle is preferably not driven, in particular via the output shaft, in the fired overrun mode. In other words, in the fired overrun mode, the motor vehicle is preferably not driven by the internal combustion engine.

[0016] The condensate is, for example, condensate water. The condensate and / or moisture results, for example, from the exhaust gas, particularly from the water contained in the exhaust gas.

[0017] For example, in the overrun mode and / or in the fired overrun mode, the standstill of the output shaft can be effected or caused by the output shaft being decoupled from the crankshaft, which in particular rotates about the crankshaft axis of rotation, by means of at least one coupling element.

[0018] The invention is based in particular on the following findings and considerations: In internal combustion engines with secondary air injection, condensate can form under certain conditions, for example due to exhaust gas pulsations in the secondary air system, for example in the secondary air line. This condensate can form primarily on duct walls or pipe walls of air-conducting ducts, for example in the form of the secondary air line, of the secondary air system. There, the condensate, also simply referred to as water, can precipitate and collect, for example, on, in particular in front of, secondary air valves or other control valves. In very cold conditions, the condensate can cause these secondary air valves or other control valves, which can be collectively referred to in particular as control and / or regulating elements, to freeze.

[0019] In contrast, the method according to the invention can prevent freezing of the secondary air system, in particular freezing of the control and regulating elements, thereby enabling the internal combustion engine or the secondary air system to be operated particularly reliably. The reliability of the secondary air system, in particular the secondary air injection, can thus be significantly increased. To achieve this, and in particular to prevent the secondary air system from freezing, a strategy can be applied in the method according to the invention to transport, i.e., remove, the condensate and / or moisture from the secondary air system, in particular from the secondary air line.For this purpose, the drying operating mode can be implemented during the engine overrun phases, i.e., during overrun mode, whereby the secondary air system can be controlled and operated to flush the secondary air system, in particular the ducts and lines of the secondary air system, using secondary air and thereby remove the condensate and / or moisture from the secondary air system. This strategy can be particularly advantageous during overrun mode, also simply referred to as engine overrun, since the exhaust gas aftertreatment system or multiple exhaust gas aftertreatment systems can be flushed with air or oxygen anyway during overrun mode. Additional air in the form of secondary air can have no influence on this, especially a negative one.Furthermore, in the method according to the invention, the drying operating mode can be carried out in the fired overrun mode, in which the internal combustion engine is in the drying operating mode, which means in particular that the secondary air injection can be carried out during the fired overrun mode. This is particularly advantageous since the fuel is introduced into the combustion chamber during the fired overrun mode and the combustion processes take place in the combustion chamber, whereby the condensate, which is flushed out, for example, by means of the secondary air, can evaporate particularly well with heat emitted in the exhaust tract, i.e. heat generated or provided by the combustion processes. The condensate can therefore evaporate particularly well than if the internal combustion engine were not in the fired overrun mode.Overall, it can be seen that, by means of the method according to the invention, condensate and / or moisture, for example, arising during engine operation, in secondary air ducts, i.e., out of secondary air ducts, can be removed. This can prevent freezing of the secondary air system, in particular the valves or regulating and control elements. Thus, a strategy for removing condensate and / or moisture from the secondary air system can be created.

[0020] For example, the internal combustion engine can be operated in a normal operating mode in which fuel is introduced into the combustion chamber via the introduction device and takes place in the combustion chamber of the internal combustion engine. The normal operating mode is preferably an operating mode of the internal combustion engine that differs from the drying mode, and in particular from the heating mode. For example, in the normal operating mode, secondary air is not introduced into the exhaust tract. This means that, for example, in the drying operating mode, no secondary air is introduced or secondary air is blown in. Preferably, the amount of fuel introduced into the combustion chamber via the introduction device in the fired overrun mode is lower than in the normal operating mode.Furthermore, the engine load of the internal combustion engine is preferably lower in the fired overrun mode than in the normal operating mode. The normal operating mode is preferably not an overrun mode of the internal combustion engine. This means that in the normal operating mode, no overrun of the internal combustion engine takes place. Preferably, in the normal operating mode, the motor vehicle is driven by the internal combustion engine via the output shaft. For example, in the fired overrun mode, the internal combustion engine is almost load-free, which means that the engine load of the internal combustion engine in the fired overrun mode is very low, for example, similarly low to when the internal combustion engine is idling.Thus, for example, the engine load in the fired overrun mode corresponds at least substantially to the engine load in the idle mode, wherein the idle mode can in particular be referred to as the idle operating mode.

[0021] Fired overrun mode can be understood, in particular, as a transitional operation from the normal operating mode and / or the heating operating mode to idle, in particular with a reduction in the engine speed. This means that the speed of the output shaft drops or is reduced, in particular continuously, in the fired overrun mode, for example, to an idle speed that the output shaft has, for example, in idle mode.

[0022] For example, the internal combustion engine has at least one electronic computing device, which can in particular be referred to as an engine controller or can be designed as an engine controller. For example, the internal combustion engine can be operated selectively in the normal operating mode, the heating operating mode, and / or the drying operating mode by means of the electronic computing device. This means that the internal combustion engine can be switched from the normal operating mode and / or the heating operating mode to the drying operating mode and vice versa by means of the electronic computing device. For example, the internal combustion engine is switched from the normal operating mode and / or the heating operating mode to the drying operating mode, in particular by means of the electronic computing device, when the internal combustion engine transitions to overrun mode and / or to fired overrun mode.

[0023] In a further embodiment, it is provided that an accelerator pedal of the motor vehicle, which is movable or adjustable between at least one position actuated by a driver and a position, in particular not actuated by the driver, is in the unactuated position in the fired overrun mode, in particular in the fired overrun mode of the drying operating mode. In other words, the accelerator pedal is not actuated by the driver in the fired overrun mode. This means that the accelerator pedal is not actuated in the fired overrun mode. The accelerator pedal can be understood in particular as an adjusting element or regulating element by means of which a driver's command regarding a torque requirement of the internal combustion engine can be detected, and in particular an engine torque can be adjusted according to the detected driver command. The accelerator pedal can in particular be referred to as an accelerator pedal.

[0024] It is preferably provided that the accelerator pedal is in the actuated position in the normal operating mode and / or in the heating operating mode of the internal combustion engine. In other words, the accelerator pedal is actuated by the driver in the normal operating mode and / or in the heating operating mode. It is preferably provided that when the accelerator pedal is moved from the actuated position to the unactuated position, the internal combustion engine, in particular selectively, switches to overrun mode and / or fired overrun mode. In other words, the internal combustion engine can switch to fired overrun mode and / or overrun mode when the driver moves the accelerator pedal from the actuated position to the unactuated position, i.e., colloquially referred to, for example, as taking his foot off the accelerator.

[0025] It is preferably provided that a throttle valve arranged in the intake tract and movable between at least two throttle valve positions, for example pivotable about at least one pivot axis, by means of which a quantity of air flowing through the intake tract, in particular introduced or to be introduced into the combustion chamber, can be adjusted or is adjusted, remains in the throttle valve position in which the throttle valve was in the operating mode preceding the fired overrun operation, for example in the normal operating mode and / or in the heating operating mode, during the transition, in particular from the normal operating mode and / or from the heating operating mode, to the fired overrun operation, that is to say in particular into the fired overrun operation of the drying operating mode.In other words, during the transition or change, for example, from normal operating mode and / or from heating mode to fired overrun mode, the throttle valve is no longer moved, particularly pivoted. If the throttle valve is in a first throttle position in normal operating mode, the throttle valve will remain in the first throttle position even after the transition from normal operating mode to fired overrun mode. In fired overrun mode, for example, an accelerator pedal position exists in which the driver does not depress the accelerator pedal, and the throttle valve is not depressed or adjusted.In a further embodiment, it is provided that the inlet point is arranged upstream of a turbine wheel arranged in the exhaust tract, in particular in the flow direction of the exhaust gas flowing through the exhaust tract and / or the secondary air flowing through the exhaust tract. In other words, the secondary air introduced into the exhaust tract via the secondary air line at the inlet point can be guided to the turbine wheel. As a result, in the drying operating mode, in particular in the overrun mode and / or in the fired overrun mode, the secondary air is introduced into the exhaust tract via the secondary air line at the inlet point upstream of the turbine wheel. In other words, in the drying operating mode, the secondary air introduced into the exhaust tract at the inlet point is guided to the turbine wheel.This allows the secondary air to be introduced into the exhaust tract particularly early, i.e., particularly far forward or upstream in relation to the flow direction, thereby heating the exhaust tract particularly effectively. The turbine wheel is preferably part of an exhaust gas turbocharger, in particular a turbine. The exhaust gas turbocharger has, for example, at least one compressor, which in particular has a compressor wheel arranged in the intake tract for compressing the air flowing through the intake tract.

[0026] In a further embodiment, it is provided that the inlet point is arranged within a cylinder head of the internal combustion engine. In other words, the secondary air line, and in particular the inlet point, extends at least partially within the cylinder head. As a result, in the drying operating mode, in particular in overrun mode and / or in fired overrun mode, the secondary air is introduced into the exhaust tract via the secondary air line at the inlet point within the cylinder head, in particular directly. The cylinder head, i.e. at least a longitudinal section of the exhaust tract extending within the cylinder head, can therefore be flowed through by the secondary air. As a result, the exhaust tract in the region of the cylinder head can be heated, whereby the exhaust tract can be heated up particularly quickly or particularly well, for example.For example, the cylinder head delimits the combustion chamber at least partially, in particular on a side facing away from the piston element, which can in particular be referred to as the upper side.

[0027] In a further embodiment, the internal combustion engine, in particular the secondary air system, has at least one fluid energy machine, by means of which the secondary air flowing through the secondary air line is conveyed through the secondary air line, in particular in the drying operating mode and / or in the heating operating mode. In other words, at least one pressure of the secondary air is provided or brought about by means of the fluid energy machine in order to introduce the secondary air via the secondary air line at the inlet point into the exhaust tract. This allows a particularly large amount of secondary air to be introduced into the exhaust tract, as a result of which the exhaust tract can be heated particularly advantageously. Furthermore, the secondary air system, in particular the secondary air line, can be flushed particularly well, as a result of which the condensate or moisture can be removed particularly well from the secondary air system.The fluid energy machine is designed, for example, as a pump or a compressor. The pump can be referred to, in particular, as a secondary air pump. The fluid energy machine is preferably arranged in the secondary air line. Furthermore, the fluid energy machine is preferably capable of being flowed through by secondary air.

[0028] In a further embodiment, it is provided that the internal combustion engine, in particular the secondary air system, has at least one valve device, arranged for example in the secondary air line, by means of which a secondary air quantity of the secondary air flowing through the secondary air line and in particular introduced into the exhaust tract at the inlet point can be adjusted or is set. As a result, the secondary air introduction can be adjusted in a particularly variable manner, i.e. as required. The valve device can be referred to in particular as a secondary air valve and / or as a control element or regulating element. By means of the valve device, for example, a secondary air quantity, referred to in particular as the first secondary air quantity, of the secondary air introduced into the exhaust tract at the inlet point can be adjusted.

[0029] In a further embodiment, the internal combustion engine, in particular the secondary air system, has at least one second valve device formed separately from the valve device, by means of which the amount of secondary air introduced into the exhaust tract, in particular at the inlet point, can be adjusted or is adjusted. The second valve device is arranged, for example, in the secondary air line, or the second valve device is arranged in a second secondary air line, in particular different from the secondary air line, through which the secondary air can flow, and which is in particular part of the secondary air system.The second secondary air line is fluidically connected to the exhaust tract, for example, via a second inlet point, in particular spaced apart from the inlet point, in particular directly, whereby the secondary air flowing through the second secondary air line is introduced into the exhaust tract at the second inlet point, in particular directly. Thus, by means of the second valve device, for example, a second secondary air quantity can be adjusted, which is the quantity of secondary air flowing through the second secondary air line and introduced into the exhaust tract at the second inlet point. The second valve device can be referred to in particular as a secondary air valve or as a control element or regulating element.

[0030] For example, it is provided that the valve device and / or the second valve device is controlled in the drying operating mode, for example during phases of towed engine operation and / or fired towed engine operation, in order to transport the condensate and / or moisture from the secondary air system, in particular from the lines or ducts of the secondary air system, by means of the secondary air. For example, the fluid energy machine is controlled, in particular by means of the electronic computing device, in the drying operating mode in order to transport the moisture and / or condensate from the secondary air system, in particular from the lines or ducts, by means of the secondary air.It can therefore be provided that during phases of towed engine operation (thrust) and / or during fired towed engine operation (fired thrust), the secondary air pump and / or associated valves or control elements are controlled in order to transport the moisture or condensate from the lines or ducts of the secondary air system.

[0031] In a further embodiment, it is provided that the respective valve device is or is adjusted between at least one respective open position and one respective closed position. Preferably, the respective valve device, and thus in particular the respective secondary air line, can be flowed through by secondary air in the respective open position, while in the closed position, the flow through the respective valve device, in particular the respective secondary air line, is stopped.

[0032] For example, it is provided that in the drying operating mode, the valve devices are opened simultaneously or alternately. In other words, in the drying operating mode, particularly during the transition to the drying operating mode, both valve devices are opened simultaneously or alternately, i.e., alternately. As a result, the secondary air system can be freed of condensate or moisture as needed. A second aspect of the invention relates to an internal combustion engine for a motor vehicle, which is designed to carry out a method according to the first aspect of the invention. 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.

[0033] Further advantages, features, and details of the invention will become apparent from the following description of preferred embodiments and from the drawings. The features and combinations of features mentioned above in the description, as well as the features and combinations of features mentioned below in the description of the figures and / or shown alone in the figures, can be used not only in the respective specified combinations, but also in other combinations or on their own, without departing from the scope of the invention.

[0034] Showing:

[0035] Fig. 1 A schematic representation of an internal combustion engine according to the invention, which can be operated by means of a method according to the invention; and

[0036] Fig. 2 is a schematic process diagram of a process according to the invention.

[0037] In the figures, identical or functionally identical elements are provided with the same reference symbols.

[0038] Fig. 1 shows a schematic representation of an internal combustion engine 1 for a motor vehicle. The motor vehicle is driven by the internal combustion engine 1. In the exemplary embodiment, the internal combustion engine 1 is designed as a reciprocating piston engine, in particular as a reciprocating piston motor.

[0039] The internal combustion engine 1 has at least one combustion chamber 2. In the exemplary embodiment, the internal combustion engine 1 has a plurality of combustion chambers 2, 3, 4, 5, which are formed separately from one another, for example. The internal combustion engine 1 is thus designed, for example, as a four-cylinder engine. Combustion processes can take place in the respective combustion chambers 2 to 5, in which a fuel-air mixture is combusted, and an exhaust gas from the internal combustion engine 1 can be generated during these combustion processes.

[0040] In the exemplary embodiment, the internal combustion engine 1 has at least one intake tract 6 through which air can flow or through which it flows, via which air can be supplied or is supplied to the respective combustion chamber 2 to 5. Furthermore, the internal combustion engine 1 in the exemplary embodiment has a throttle valve 7 arranged in the intake tract 6 and movable between at least two throttle valve positions, by means of which throttle valve 7 an air quantity flowing through the intake tract 6 can be adjusted or is adjusted. For example, a first of the positions is an open position in which air flows through the intake tract 6, whereby the air is introduced into the respective combustion chamber 2 to 5 via the intake tract 6. For example, a second of the throttle valve positions is a closed position in which air does not flow through the intake tract 6.

[0041] The internal combustion engine 1 has at least one fuel introduction device 8 for introducing fuel into the, in particular, respective combustion chambers 4 to 5. In the exemplary embodiment, a plurality of fuel introduction devices 8 are provided, wherein, for example, one of the respective fuel introduction devices 8 is assigned to the respective combustion chamber 2 to 5, by means of which fuel can be introduced or is introduced into the respective combustion chamber 2 to 5. The respective fuel introduction device 8 is designed, for example, as a respective injector, in particular for injecting the fuel into the respective combustion chamber 2 to 5.

[0042] Furthermore, the internal combustion engine 1 has at least one exhaust tract 9 through which the exhaust gas from the respective combustion chamber 2 to 5 can flow, via which the exhaust gas from the respective combustion chamber 2 to 5 can be discharged.

[0043] In the exemplary embodiment, at least one exhaust gas aftertreatment device 10, which is designed, for example, as a catalytic converter, is arranged in the exhaust tract 9. Furthermore, in the exemplary embodiment, for example, a turbine wheel 11 is arranged, which is preferably arranged upstream of the exhaust gas aftertreatment device 10 in the flow direction of the exhaust gas flowing through the exhaust tract 9. In particular, it is provided that the turbine wheel 11 can be driven or is driven by the exhaust gas flowing through the exhaust tract 9, preferably in order to drive a compressor wheel arranged in the intake tract 6 for compressing the air flowing through the intake tract 6.

[0044] In the present exemplary embodiment, the exhaust tract 9, which can in particular be referred to as an exhaust system, or a turbine having the turbine wheel 11, is designed with multiple flow paths, in particular with two flows. Thus, the exhaust tract 9 has, for example, a first line section 9a through which the exhaust gas can flow and via which the exhaust gas can be discharged from a first and a fourth of the combustion chambers 2, 5, and the exhaust tract 9 has at least one second line section 9b through which the exhaust gas can flow and via which the exhaust gas can be discharged from a second and a third of the combustion chambers 3, 4. The first line section 9a is, for example, fluidically connected to the turbine at a first connection point, in particular directly, and the second line section 9b is, for example, fluidically connected to the turbine at a second connection point, in particular directly, which is different from the first connection point.

[0045] The internal combustion engine 1 has at least one secondary air line 12 through which secondary air can flow or through which it flows, which is, for example, part of a secondary air system 13 of the internal combustion engine 1. The secondary air line 12 can be understood, for example, as a secondary air line section. The secondary air line 12 or the secondary air system 13 is fluidically connected, in particular directly, to the exhaust tract 9 at at least one inlet point 14, whereby the secondary air flowing through the secondary air line 12 can be introduced or is introduced into the exhaust tract 9 at the inlet point 14, in particular directly, via the secondary air line 12 or by means of the secondary air system 13. In the exemplary embodiment shown in Fig. 1, several, for example four, such inlet points 14, 15, 16, 17 are provided.For example, a first and a fourth of the inlet points 14, 17 are fluidically connected, in particular directly, to the first line section 9a of the exhaust tract 9. For example, a second and a third of the inlet points 15, 16 are fluidically connected, in particular directly, to the second line section 9b of the exhaust tract 9. The secondary air system 13, in particular the secondary air line 12, has, for example, a plurality of line elements 18, 19, 20 through which the secondary air can flow. For example, the secondary air flowing through a first of the power elements 18 can be divided between a second and a third line element 19, 20. Thus, the second and the third line element 19, 20 are, for example, in particular fluid-mechanically, connected or switchable in parallel to one another, i.e., can flow through them in parallel.In the flow direction of the secondary air flowing through the line elements 18, 19, 20, for example, at least one branching point is arranged between the first line element 18 and the second and third line elements 19, 20, wherein secondary air flowing through the first line element 18 can be introduced into the second and third line elements 19, 20 via the branching point. For example, the second line element 19 is fluidically connected, in particular directly, to the first and fourth inlet points 14, 17. For example, the third line element 20 is fluidically connected, in particular directly, to the second and third inlet points 15, 16. Thus, the secondary air flowing through the second line element 18 can be introduced into the exhaust tract 9, in particular into the first line section 9a, at the first and fourth inlet points 14, 17, in particular directly.Furthermore, the secondary air flowing through the second line element 20 can be introduced at the second and third inlet points 15, 16, in particular directly, into the exhaust gas tract 9, in particular into the second line section 13.

[0046] In the exemplary embodiment shown in Fig. 1, the internal combustion engine 1, in particular the secondary air system 13, has at least one fluid energy machine 21, through which the secondary air can flow, in particular, and which is designed, for example, as a pump or a compressor. The pump can be referred to in particular as a secondary air pump. It is provided that the secondary air flowing through the secondary air line 12 or the secondary air system 13 can be conveyed or is conveyed through the secondary air line 12 or the secondary air system 13 by means of the fluid energy machine 21. In the exemplary embodiment, the fluid energy machine 21 is arranged in the secondary air line 12, in particular in the first line element 18.

[0047] The secondary air system 13 is designed, for example, as a secondary air circuit. For example, the secondary air system 13, in particular the secondary air line 12, is fluidically connected, in particular directly, to the intake tract 6, preferably bypassing or avoiding the respective combustion chamber 2 to 5. As a result, for example, the air flowing through the intake tract 6 can be introduced via the secondary air line 12 as secondary air, in particular bypassing the respective combustion chamber 2 to 5, at the respective inlet point 14 to 17, in particular directly, into the exhaust tract 9. For example, it can be provided that the fluid energy machine 21 is the compressor arranged in the intake tract 6. For example, the secondary air system 13 has at least one control and / or regulating device 22.By means of the control and / or regulating device 22, a secondary air quantity of the secondary air flowing through the secondary air system 13, in particular the secondary air line 12, can be adjusted. In the exemplary embodiment shown in Fig. 1, the control and / or regulating device 22 has at least one first valve device 23, which is arranged, for example, in the second line element 19. It is preferably provided that the secondary air quantity of the secondary air flowing through the secondary air line 12, in particular a secondary air quantity of the second line element 18, can be adjusted or is adjusted by means of the first valve device 23. Furthermore, the control and / or regulating device 22 has at least one second valve device 24 which is formed separately from the valve device 23 and is arranged, for example, in the third line element 20.It is preferably provided that the secondary air flowing through the secondary air line 12, in particular flowing through the third line element 20, is adjustable or set by means of the second valve device 23. In other words, it is preferably provided that the secondary air quantity introduced into the exhaust tract 9, in particular at the respective inlet point 14 to 17, is adjustable or set by means of the valve device 23, which can in particular be referred to as the first valve device 23, and / or by means of the second valve device 24. The control and / or regulating device 22, in particular the first and / or the second valve device 24, is preferably arranged downstream of the fluid energy machine 21, in particular in the flow direction of the secondary air system 13 or of the secondary air flowing through the secondary air line 12.The respective valve device 23, 24 can be referred to, in particular, as a respective control and / or regulating valve for the secondary air. Secondary air valves in the form of valve devices 23, 24 are arranged in the secondary air circuit, which selectively release or block the secondary air, for example, coming from the pump or compressor, to the cylinder head and / or to the exhaust aftertreatment device 10.

[0048] For example, the secondary air system 13 has at least one check valve 25, which is arranged, for example, in the secondary air line 12, in particular in the first line element 18. For example, the at least one check valve 25 is arranged upstream of the control and / or regulating device 22 and / or downstream of the fluid energy machine 21, in particular in the flow direction of the secondary air described in the secondary air line.

[0049] The secondary air introduced into the exhaust tract 9 by means of the secondary air system 13, in particular at the respective inlet point 14 to 17, can heat the exhaust tract 9, in particular the exhaust gas aftertreatment device 10, for example by post-oxidation. For this purpose, the secondary air introduced into the exhaust tract can be guided at least close to the exhaust gas aftertreatment device 10. Post-oxidation can be understood, for example, as the combustion taking place in the exhaust tract 9 of unburned fuel that has passed from the respective combustion chamber 2 to 5 into the exhaust tract 9. In particular, it can be seen that the secondary air introduced into the exhaust tract 9 by means of the secondary air system 13 bypasses the or all of the combustion chambers 2 to 5 of the internal combustion engine 1 and thus does not flow through the combustion chambers 2 to 5 or through any of the combustion chambers 2 to 5 of the internal combustion engine 1.

[0050] Fig. 2 shows a schematic process diagram to illustrate a method for operating the internal combustion engine 1. The internal combustion engine 1 is thus designed to carry out the method.

[0051] In order to be able to operate the internal combustion engine 1, in particular the secondary air system, particularly reliably, and in particular to be able to particularly increase security against freezing of components of the internal combustion engine 1, it is provided that the internal combustion engine 1 is operated or can be operated in a drying operating mode 26, in particular for removing condensate and / or moisture from the secondary air system 13 or the secondary air line 12. In the drying operating mode 26, the secondary air flowing through the secondary air system 13 or the secondary air line 12 is introduced into the exhaust tract 9 at the respective inlet point 14 to 17, in particular directly, by means of the secondary air system 13, i.e. via the secondary air line 12.This means that the introduction, in particular blowing in, of the secondary air takes place, i.e., is carried out, by means of the secondary air system in the drying operating mode 26. Furthermore, in the drying operating mode 26, the internal combustion engine 1 is in an overrun mode 27, in which the introduction of fuel, in particular via the respective fuel introduction device 8, into the respective combustion chambers 2 to 5 is omitted, and no combustion processes take place in the respective combustion chambers 2 to 5. The overrun mode 27 can therefore be referred to, in particular, as an unfired overrun mode 27.Alternatively, it is provided that in the drying operating mode 26, the internal combustion engine 1 is in a fired overrun mode 28, which is in particular different from the unfired overrun mode 27, in which fuel is introduced, in particular injected, into the respective combustion chamber 2 to 5 via the respective fuel introduction device 8 and the combustion processes take place in the respective combustion chamber 2 to 5. As a result, the condensate or moisture that can form or has formed in the secondary air system 13 during regular engine operation due to exhaust gas pulsations can be transported away from the secondary air system 13, i.e. removed, in order to prevent, for example, freezing of at least a partial area or a partial component of the secondary air system 13.The secondary air system 13, in particular the secondary air line 12, can thus be flushed, so to speak, by means of the secondary air in the drying operating mode 26, in particular to remove the condensate and / or moisture from the secondary air system 13. This flushing of the secondary air system 13 can be carried out particularly effectively in the unfired overrun mode 27 and / or in the fired overrun mode 28, since, for example, there is no exhaust gas or only a very small amount of exhaust gas in the exhaust tract 9. In particular, a renewed entry of exhaust gas into the secondary air system 13 due to exhaust gas pulsations can be avoided.

[0052] Regular engine operation can be understood, in particular, as a normal operating mode 29 of the internal combustion engine 1. In particular, it is provided that an engine load of the internal combustion engine 1, also simply referred to as load, is smaller, in particular significantly smaller, in the fired overrun mode 28 than in the normal operating mode 29. For example, the engine load in the fired overrun mode 28 is less than 10%, in particular less than 5, 3, or 1%, of the engine load in the normal operating mode 29. The internal combustion engine 1 is thus operated, in particular, almost load-free in the fired overrun mode 28. For example, the engine load in the unfired overrun mode 27 is zero.

[0053] For example, it is provided that the internal combustion engine 1 transitions from the normal operating mode 29, in which the internal combustion engine 1 is neither in the fired overrun mode 28 nor in the unfired overrun mode 27, to the drying operating mode 26 as soon as the internal combustion engine 1 goes into overrun, that is to say, in particular, from the normal operating mode 29, into the unfired overrun mode 27 or into the fired overrun mode 28. To transition to the drying operating mode 26, an electronic computing device, which is designed, for example, as an engine controller, can control the fluid energy machine 21 and / or the control and regulating device 22, that is to say at least one of the valve devices 23, 24, for example for a certain time, in particular in order to introduce the secondary air into the exhaust tract 9 by means of the secondary air system.For example, the drying operating mode 26 can be switched off, in particular by means of the electronic computing device, for example as soon as the driver or the engine control unit requests load. This means that the internal combustion engine 1 can transition from the drying operating mode 26, in particular again, to the normal operating mode 29. For this purpose, the fluid energy machine 21 and / or the control and regulating device 22 can, for example, be controlled, in particular by means of the electronic computing device, in particular switched off again, for example as soon as the driver and / or the engine control unit requests load. In particular, it is provided that the internal combustion engine 1, for example in the drying operating mode 26, can be operated or is operated optionally in the unfired overrun mode 27 or in the fired overrun mode 28.

[0054] Thus, for example, it is provided that in the unfired overrun mode 27 and / or in the fired overrun mode 28, an accelerator pedal 32 of the motor vehicle, which can be moved between at least one position 30 actuated by the driver and an unactuated position 31, is in the unactuated position 31, and in particular in the normal operating mode 29 is in the actuated position 30.

[0055] For example, it is provided that the accelerator pedal 32 is in the activated position 30 in the normal operating mode 29 of the internal combustion engine 1, and the internal combustion engine 1 transitions, upon moving the accelerator pedal 32 from the activated position 30 to the deactivated position 31, into the fired overrun mode 28 or into the unfired overrun mode 27. It is preferably provided that the throttle valve 7, during the transition from the normal operating mode 29 to the fired overrun mode 28, remains in the throttle valve position in which the throttle valve 7 was in the, in particular preceding, normal operating mode 29. This means that, in particular when the internal combustion engine 1 transitions to the fired overrun mode 28, the throttle valve position in the drying operating mode 26 is not changed compared to the, in particular preceding, normal operating mode 29, i.e., remains constant.In particular, throttle valve 7 is not in a closed throttle position during fired overrun mode 28. This means that air can enter the respective combustion chambers 2 to 5 via throttle valve 7.

[0056] In the exemplary embodiment, it is provided that the respective inlet point 14 to 17 is arranged within a cylinder head 33 of the internal combustion engine 1, whereby, in particular in the drying operating mode 26, the secondary air is introduced into the exhaust tract 9 by means of the secondary air system 13 or via the secondary air line 12 at the respective inlet point 14 to 17 within the cylinder head 33. Furthermore, it is provided in the exemplary embodiment that, in particular in the drying operating mode 26, the secondary air is introduced into the exhaust tract 9 by means of the secondary air system 13 or via the secondary air line 12 at the respective inlet point 14 to 17 upstream of the turbine wheel 11.

[0057] Preferably, the respective valve device 23, 24 is adjustable between a respective open position and a respective closed position. For example, in the drying operating mode 26, the valve devices 23, 24 are opened simultaneously or are opened alternately. The valve devices 23, 24 can thus be opened simultaneously, in particular synchronously, or can be opened alternately, i.e., alternately.

[0058] Numerals such as "first," "second," "third," etc., are intended solely for differentiation and do not indicate any order. This means that the corresponding numerals can be interchanged at will.

[0059] List of reference symbols

[0060] 1 internal combustion engine

[0061] 2 first combustion chamber

[0062] 3 second combustion chamber

[0063] 4 third combustion chamber

[0064] 5 fourth combustion chamber

[0065] 6 Intake tract

[0066] 7 Throttle valve

[0067] 8 Fuel injection device

[0068] 9 Exhaust system

[0069] 9a first line section

[0070] 9b second line section

[0071] 10 Exhaust aftertreatment system

[0072] 11 Turbine wheel

[0073] 12 Secondary air line

[0074] 13 Secondary air system

[0075] 14 first discharge point

[0076] 15 second discharge point

[0077] 16 third discharge point

[0078] 17 fourth discharge point

[0079] 18 first line element

[0080] 19 second line element

[0081] 20 third line element

[0082] 21 Fluid energy machine

[0083] 22 Control and / or regulating device

[0084] 23 first valve device

[0085] 24 second valve device

[0086] 25 Check valve

[0087] 26 Drying mode

[0088] 27 unfired push operation

[0089] 28 fired push operation

[0090] 29 Normal operating mode

[0091] 30 actuated position

[0092] 31 unactuated position

[0093] 32 Accelerator pedal

[0094] 33 cylinder head

Claims

Patent claims 1. A method for operating an internal combustion engine (1) for a motor vehicle, in which the internal combustion engine (1) has at least one combustion chamber (2), at least one fuel introduction device (8) for introducing fuel into the combustion chamber (2), an exhaust tract (9) through which an exhaust gas from the combustion chamber (2) of the internal combustion engine (1) can flow, and at least one secondary air line (12) through which secondary air can flow, which is fluidically connected to the exhaust tract (9) at an inlet point (14), whereby the secondary air flowing through the secondary air line (12) can be introduced into the exhaust tract (9) at the inlet point (14) via the secondary air line (12), characterized in that the internal combustion engine (1) is operated in a drying operating mode (26),in which the secondary air flowing through the secondary air line (12) is introduced into the exhaust tract (9) at the inlet point (14) via the secondary air line (12) and, • the internal combustion engine (1) is in overrun mode (27), in which the introduction of fuel into the combustion chamber (2) is omitted and no combustion processes take place in the combustion chamber (2), or • the internal combustion engine (1) is in a fired overrun mode (28), in which fuel is introduced into the combustion chamber (2) via the introduction device (8) and the combustion processes take place in the combustion chamber (2).

2. Method according to claim 1, characterized in that a switch is provided between at least one position (30) operated by a driver and a the accelerator pedal (32) of the motor vehicle which is movable in the unactuated position (31) is in the fired overrun mode (28) in the unactuated position (31).

3. Method according to claim 2, characterized in that the accelerator pedal (32) is in the actuated position (30) in a normal operating mode (29) of the internal combustion engine (1), and the internal combustion engine (1) transitions into the fired overrun mode (28) when the accelerator pedal (32) is moved from the actuated position (30) to the unactuated position (31), wherein a throttle valve (7) arranged in an intake tract (6) of the internal combustion engine (1) through which air can flow and movable between at least two throttle valve positions, by means of which a quantity of air flowing through the intake tract (6) can be adjusted, remains in the throttle valve position in which the throttle valve (7) was in the normal operating mode (26) during the transition from the normal operating mode (29) to the fired overrun mode (28).

4. Method according to one of the preceding claims, characterized in that the inlet point (14) is arranged upstream of a turbine wheel (11) arranged in the exhaust tract (9), whereby in the drying operating mode (26) the secondary air is introduced into the exhaust tract (9) via the secondary air line (12) at the inlet point (14) upstream of the turbine wheel (11).

5. Method according to one of the preceding claims, characterized in that the inlet point (14) is arranged within a cylinder head (33) of the internal combustion engine (1), whereby in the drying operating mode (26) the secondary air is introduced into the exhaust tract (9) via the secondary air line (12) at the inlet point (14) within the cylinder head (33).

6. Method according to one of the preceding claims, characterized by a fluid energy machine (21), by means of which the secondary air line (12) flowing secondary air is conveyed through the secondary air line (12).

7. Method according to one of the preceding claims, characterized by at least one valve device (23) by means of which a secondary air quantity of the secondary air flowing through the secondary air line (12) can be adjusted.

8. Method according to claim 7, characterized by at least one second valve device (24) formed separately from the valve device (23), by means of which the amount of secondary air introduced into the exhaust tract (9) can be adjusted.

9. Method according to claim 8, characterized in that the respective valve device (23) is adjustable between at least one respective open position and one respective closed position, wherein in the drying operating mode (26) the valve devices (23, 24) are opened simultaneously or are opened alternately.

10. Internal combustion engine (1) for a motor vehicle, which is designed to carry out a method according to one of the preceding claims.

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