Internal combustion engine for a motor vehicle, motor vehicle and method

Description

[0001] The invention relates to an internal combustion engine for a motor vehicle according to the preamble of patent claim 1. Furthermore, the invention relates to a motor vehicle and a method for operating an internal combustion engine of a motor vehicle according to the preamble of patent claim 7.

[0002] EP 3 020 934 B1 discloses a vehicle with an internal combustion engine having a crankcase and a charging device, with a crankcase ventilation device having at least one inertia-based oil separation device with at least one inertia-based oil separator, an oil return line returning separated oil to the crankcase, and a suction jet pump driven by compressed air from the charging device and generating a negative pressure to drive blow-by gas.The crankcase ventilation device comprises a pump control valve that regulates and / or controls the flow of compressed air through the suction jet pump and that has a loss part that is arranged so that force is applied against a valve seat and is lifted out of the valve seat against the force when a threshold pressure difference between a valve inlet and a valve outlet is exceeded or when an input-side threshold pressure is exceeded, so that the pump control valve is opened.

[0003] Furthermore, EP 3 034 820 A2 discloses a venting device for discharging blow-by gas from an engine block of an internal combustion engine, comprising a first inlet opening and a second inlet opening spaced from the first inlet opening for admitting blow-by gas originating from the engine block into the venting device, and comprising at least one oil separator for separating oil from the blow-by gas. The venting device comprises a first supply channel for supplying blow-by gas to the at least one oil separator, wherein the first supply channel runs from the first inlet opening to such an oil separator, and a second supply channel for supplying blow-by gas to the at least one oil separator, wherein the second supply channel runs from the second inlet opening to a connection point arranged upstream of the at least one oil separator in the first supply channel.

[0004] It is an object of the invention to provide an internal combustion engine for a motor vehicle, a motor vehicle having such an internal combustion engine and a method for operating such an internal combustion engine, so that oil can be separated particularly advantageously from a blow-by gas of the internal combustion engine.

[0005] Furthermore, EP 2 905 438 A1 discloses a blow-by gas processing device for an internal combustion engine configured as a V-engine. Furthermore, an oil return structure for an engine is known from JP H05 58807 U. Furthermore, DE 10 2008 029 904 A1 discloses a device for crankcase ventilation and recirculation of the ventilation gases into the combustion chamber of a turbocharged internal combustion engine. Furthermore, DE 42 39 108 A1 discloses a device for ventilating the crankcase of an internal combustion engine with V-shaped cylinders.

[0006] This object is achieved according to the invention by an internal combustion engine for a motor vehicle having the features of patent claim 1, by a motor vehicle having such an internal combustion engine having the features of patent claim 6, and by a method for operating such an internal combustion engine of such a motor vehicle having the features of patent claim 7. Advantageous embodiments are the subject of the dependent patent claims and the description.

[0007] A first aspect of the invention relates to an internal combustion engine for a motor vehicle, which is preferably designed as a motor vehicle, in particular as a passenger car, commercial vehicle, or truck. The internal combustion engine has an output shaft, designed in particular as a crankshaft, via which the motor vehicle can be driven by the internal combustion engine. The internal combustion engine comprises a crankcase, referred to in particular as a cylinder crankcase, which at least partially delimits at least one cylinder and a crank chamber of the internal combustion engine. The output shaft is arranged at least partially within the crankcase and thus in the crank chamber, wherein the output shaft is rotatable relative to the crankcase.

[0008] A piston is preferably arranged in the cylinder so as to be translationally movable relative to a cylinder wall of the cylinder. The cylinder wall can be formed by the crankcase. The cylinder wall and the piston partially delimit a combustion chamber of the internal combustion engine. The internal combustion engine has an intake tract through which air can flow and an exhaust tract through which exhaust gas from the internal combustion engine can flow. Air can be supplied to the combustion chamber via the intake tract, and the exhaust gas can be discharged from the combustion chamber via the exhaust tract. The air flowing through the intake tract can in particular be referred to as fresh air. At least one compressor can be arranged in the intake tract, by means of which the air flowing through the intake tract can be compressed and conveyed into the combustion chamber. The internal combustion engine preferably has a cylinder head which partially delimits the combustion chamber.An intake duct through which air can flow can run within the cylinder head, which forms part of the intake tract, and the air flowing through the intake duct can be fed to the combustion chamber. In other words, the intake tract can run at least partially within the cylinder head, so that the air flowing through the intake duct can be guided through the cylinder head via the intake duct. When the internal combustion engine is activated, combustion processes take place in the combustion chamber. A fuel-air mixture comprising fresh air is combusted, resulting in the exhaust gas of the internal combustion engine. These combustion processes can in particular be referred to as combustion.

[0009] The internal combustion engine has at least two oil separation devices, in particular designed separately from one another, by means of which oil can be separated from a blow-by gas discharged from the crankcase, in particular the crank chamber, and fed to the oil separation devices. The oil separation devices can in particular be referred to as oil separators or oil mist separators. The blow-by gas can be understood in particular as exhaust gas which reaches or flows from the combustion chamber, in particular via a gap which is at least partially formed by the piston or at least one piston ring arranged on the piston and the cylinder wall, into the crankcase, in particular into the crank chamber. The blow-by gas can comprise the oil, wherein the oil can be separated from the blow-by gas, for example, when the blow-by gas flows from the combustion chamber into the crank chamber.The oil, which can wet the cylinder wall and / or the piston rings, for example, can be entrained by the blow-by gas as it flows through the gap, whereby the oil can be absorbed by the blow-by gas. In addition, the oil can be provided in the crankcase or the crank chamber, for example for lubrication, in particular for a bearing of the output shaft, and can be absorbed in the crank chamber by the blow-by gas. In particular, because the blow-by gas can comprise the oil, the blow-by gas can be referred to in particular as oil mist. The removal of the blow-by gas from the crank chamber or the separation of the oil from the blow-by gas can be referred to in particular as crankcase ventilation. For example, the blow-by gas can be removed from the crank chamber via a line element and fed to the oil separation devices.

[0010] Preferably, one of the oil separation devices is designed as a full-load oil separator, and the other of the oil separation devices is preferably designed as a part-load oil separator. This can be understood, in particular, that in an operating state of the internal combustion engine referred to as full-load, the oil can be separated or is separated from the blow-by gas by means of the full-load oil separator, wherein the separation of the oil from the blow-by gas by means of the part-load oil separator is preferably omitted, and in an operating state of the internal combustion engine different from full load and referred to as part-load, the oil can be separated or is separated from the blow-by gas by means of the part-load oil separator, wherein the separation of the oil from the blow-by gas by means of the full-load oil separator is preferably omitted.In the operating state referred to as full load, for example, the torque of the internal combustion engine or the output shaft can be particularly high and correspond, for example, to the maximum torque of the internal combustion engine. In the operating state referred to as partial load, the torque of the internal combustion engine or the output shaft can be particularly low, in particular lower than at full load and can, for example, correspond to less than 50 percent of the maximum torque of the internal combustion engine.

[0011] When the oil is separated from the blow-by gas by means of the oil separation devices, the blow-by gas flows through the respective oil separation device, whereby the oil is separated from the blow-by gas by means of the respective oil separation device and the blow-by gas is thus cleaned of the oil by means of the respective oil separation device and is therefore preferably free of the oil after separation. The blow-by gas freed of the oil by means of the oil separation devices during the separation of the oil can be fed to the intake tract after separation and thus introduced into the intake tract. At full load, the blow-by gas is preferably introduced into the intake tract upstream of the compressor in the flow direction of the air flowing through the intake tract after the oil has been separated by means of the full-load oil separator.At partial load, the blow-by gas is preferably introduced into the intake tract, in particular into the inlet duct, after the oil has been separated by means of the partial load oil separator in the flow direction of the air flowing through the intake tract downstream of the compressor.

[0012] The internal combustion engine comprises a return device through which the oil separated by the oil separation devices can flow, and via which the oil separated from the blow-by gas by the oil separation devices can be guided or introduced from the oil separation devices into a reservoir. The reservoir is preferably designed as an oil pan, which is intended to collect the oil. The oil pan can in particular be referred to as an oil sump. The reservoir is preferably arranged in the installation position of the internal combustion engine in the vertical direction of the vehicle below the oil separation devices, wherein the internal combustion engine assumes the installation position in the motor vehicle in its fully manufactured state. The internal combustion engine assumes the installation position in a fully manufactured state of the motor vehicle.The reservoir can, for example, be arranged below the crankcase in the installation position of the internal combustion engine in the vertical direction of the vehicle or can be arranged in the crankcase or the crank chamber.

[0013] In order to be able to separate the oil particularly advantageously from the blow-by gas, the return device has at least one first return channel through which a first part of the oil separated from the blow-by gas by means of a first of the oil separation devices can flow, via which the first part of the separated oil can be guided from the first oil separation device into the reservoir, and at least one second return channel which is at least partially spaced from the first return channel and through which a second part of the oil separated from the blow-by gas by means of the second oil separation device can flow, via which the second part of the separated oil can be guided from the second oil separation device into the reservoir.In other words, the return device comprises the return channels that are at least partially separated from one another, in particular formed separately from one another, wherein the first oil separation device is fluidically connected to the reservoir via the first return channel and the second oil separation device is fluidically connected to the reservoir via the second return channel, whereby the first part of the oil can be introduced into the reservoir via the first return channel and the second part of the oil can be introduced into the reservoir via the second return channel. The return channel assigned to the full-load oil separator can in particular be referred to as a full-load separation channel, and the return channel assigned to the part-load oil separator can in particular be referred to as a part-load separation channel.

[0014] The invention is based in particular on the following findings and considerations: A filtration efficiency of the respective oil separation device can depend, in particular directly, on a pressure loss, particularly referred to as pressure loss potential, across the oil separation device, viewed in the flow direction of the oil. The pressure loss can be understood in particular as a pressure difference, in particular a hydrostatic pressure difference, between two pressures, wherein a first of the pressures can be a pressure of the oil in the oil separation device and the second of the pressures can be a pressure of the oil in the return device or in the reservoir. The filtration efficiency can be understood in particular as an efficiency of the oil separated by means of the respective oil separation device, in particular a separation degree. Typically, a particularly high filtration efficiency can be achieved with a particularly high pressure loss.In addition, the particularly high pressure loss makes it possible to achieve particularly high levels of robustness against oil tearing. Oil tearing can be understood in particular as oil being able to flow upwards in the vertical direction of the vehicle via the return device, which is particularly referred to as the oil return channel, contrary to the originally intended flow direction of the oil flowing through the return device, into the respective oil separation device, in particular into a separation chamber of the respective oil separation device and / or even into the intake tract, in particular in the flow direction of the air flowing through the intake tract upstream of the compressor and / or into the inlet duct. If the oil is able to flow upwards in the vertical direction of the vehicle into the oil separation device, the filtration efficiency of the oil separator, for example, can drop particularly sharply.In particular, if the oil can enter the intake tract, the oil can enter the combustion chamber via the intake tract and participate in the combustion processes or be burned there, which can particularly increase pollutant emissions from the internal combustion engine.

[0015] In a conventional internal combustion engine, the return device can have only one return channel, through which the first and second portions of the separated oil can be conveyed from the respective oil separator into the reservoir. In other words, in a conventional internal combustion engine, the two oil separators can have a common return channel. In this case, one of the oil separators can be arranged vertically below the other oil separators, particularly due to space constraints. For example, the partial-load oil separator can be arranged vertically below the full-load oil separator.As a result, a geodetic height difference, particularly referred to as geodetic height, of the respective oil separation device, in particular of the lower oil separation devices in the vehicle's vertical direction, between the respective oil separation device and the reservoir can be particularly small. The geodetic height difference can be understood as a distance running in the vehicle's vertical direction between two points, wherein a first of the points can be arranged, for example, in a respective outlet opening of the respective oil separation device and the second point can be arranged in the reservoir. The respective oil separation device is fluidically connected to the return device via the respective outlet opening. The first point is preferably a lowest point of the outlet opening in the vehicle's vertical direction. For example, the second point is a highest point of the reservoir in the vehicle's vertical direction.Due to the particularly small geodetic height difference, the pressure loss potential and thus the filtration efficiency of the respective oil separation device in a conventional internal combustion engine can be particularly low. Due to the particularly small geodetic height difference, as well as the installation position of the internal combustion engine in the vehicle and possibly due to particularly fast cornering of the vehicle, the geodetic height difference may no longer be sufficient, so that the oil can be forced upwards in the vertical direction of the vehicle by the return device, contrary to the originally intended flow direction of the oil, into the oil separation devices, in particular into the separation chambers, or even into the intake tract.

[0016] In contrast, in the internal combustion engine according to the invention, the geodetic height difference or distance is particularly high, particularly due to the two return channels being spaced apart from each other. This allows the oil to be cleanly directed downwards into the reservoir in the vertical direction of the vehicle in all driving conditions of the motor vehicle, especially when cornering, even under particularly high lateral acceleration, and from there cannot flow upwards to the oil separation devices. Due to the geodetic height difference, the pressure loss potential can be significantly increased, thereby significantly increasing the filtration efficiency of the respective oil separation devices.In other words, the oil separation devices can be arranged particularly high in the vehicle's vertical direction in the internal combustion engine and can therefore be moved particularly far upwards compared to a conventional internal combustion engine, whereby the geodetic height difference or distance can be particularly increased.

[0017] Furthermore, the return channels have at least one longitudinal region through which the oil can flow and which runs within a housing wall of the crankcase, which is delimited in its circumferential direction at least partially, in particular completely circumferentially, by the housing wall, in particular directly. In other words, the two parts of the oil are guided through the housing wall of the crankcase over the respective longitudinal region of the return channels. In other words, the oil discharged from the respective oil separation device can be received by the respective return channel, in particular at an interface to the cylinder head, and can thereby be guided downwards through the crankcase in the vertical direction of the vehicle to the reservoir.As a result, the oil separated from the blow-by gas by means of the oil separation devices can be guided into the reservoir in a particularly advantageous manner, whereby, for example, manufacturing costs or manufacturing expenditure of the internal combustion engine and / or the installation space of the internal combustion engine can be kept particularly low.

[0018] In addition, the internal combustion engine comprises respective opening points at which the return channels open into at least one receiving area, defined by the reservoir, in particular directly, in which the oil can be received. In other words, the oil flowing through the respective return channel can be discharged or guided out of the respective return channel via the respective opening point and introduced into the reservoir, wherein the respective return channel is fluidically connected to the receiving area by means of the respective opening point. As a result, the oil flowing through the return channels can be introduced into the reservoir in a particularly advantageous manner.

[0019] Furthermore, at least one of the outlet points is arranged in the installation position of the internal combustion engine in the vertical direction of the vehicle below an oil level, in particular referred to as oil level, of the oil located in the reservoir.In other words, particularly when the motor vehicle is at rest and / or the motor vehicle is on a level roadway and / or the internal combustion engine is in a deactivated state and / or when the oil held in the receiving area or the reservoir has a temperature of 25° Celsius and / or the internal combustion engine comprises a defined amount of oil, referred to in particular as the target oil quantity, which is provided for normal operation of the internal combustion engine in the fully manufactured state of the internal combustion engine, at least one of the outlet points in the installed position of the internal combustion engine in the vertical direction of the vehicle is arranged below the oil level, referred to in particular as the target oil level.The term "at rest" refers, in particular, to the fact that the motor vehicle is not moving and thus not moving relative to the roadway. The term "level" refers, in particular, to the fact that the roadway is not inclined, i.e., does not have an incline. The deactivated state of the internal combustion engine is an operating state of the internal combustion engine that differs from the activated state; in the deactivated state, combustion processes in the combustion chamber cease.

[0020] The return channels each have at least one length region through which the oil can flow, which is arranged downstream of the respective length region in the flow direction of the oil flowing through the return channels, which length region runs within a reservoir wall of the reservoir and is at least partially delimited in its circumferential direction by the reservoir wall.

[0021] In a conventional internal combustion engine, an oil siphon through which the oil can flow can be arranged, for example in the cylinder head, between the oil separator and the reservoir in the flow direction of the oil flowing from the respective oil separator to the reservoir. For example, the oil siphon has at least one curved partial area in which the oil can collect, wherein the oil collected in the partial area can flow out of the partial area, in particular when a fill level of the partial area is exceeded, and can thus be drained from the oil siphon and fed into the return device, for example. In the conventional internal combustion engine, the oil siphon can be arranged, in particular, directly on the oil separator and can be referred to in particular as a birdbath.The oil siphon can perform a function, particularly referred to as a sealing function, since the oil siphon can be gas-impermeable due to the oil located there. In a conventional internal combustion engine, a second geodetic height difference or a second distance between the oil siphon and the respective oil separation device in the vertical direction of the vehicle can be particularly small, whereby the pressure loss potential and thus the filtration efficiency of the respective oil separation device can be particularly low. Because in the internal combustion engine according to the invention at least one of the opening points is arranged in the installed position of the internal combustion engine in the vertical direction of the vehicle below the oil level of the oil located in the oil pan, the oil siphon of the conventional internal combustion engine can be omitted, since the reservoir, in particular the oil pan, can take over the function of the conventional oil siphon.In other words, the oil siphon can be positioned particularly far down in the vertical direction of the vehicle, particularly compared to a conventional internal combustion engine, allowing the second distance or the second geodetic height difference to be significantly increased. The geodetic height difference can correspond to the second geodetic height difference. This can, for example, significantly increase the filtration efficiency or the pressure loss potential.

[0022] In a further embodiment of the invention, the internal combustion engine comprises the reservoir, and the oil separation devices are each equidistant from the reservoir in the vertical direction of the vehicle when the internal combustion engine is installed. This can be understood in particular to mean that the respective first point of the respective oil separation device is each equidistant from the second point in the vertical direction of the vehicle. As a result, both oil separation devices have the same geodetic height difference or the same value of the geodetic height difference, whereby the pressure loss potential for both oil separation devices can be particularly increased. Because the internal combustion engine according to the invention comprises the reservoir in the embodiment, the reservoir in the embodiment is part of the scope of protection of the internal combustion engine according to the invention.

[0023] For example, the respective return channel can extend at least partially within a reservoir wall, which at least partially delimits the reservoir, and can be guided below the target oil level of the reservoir in the vertical direction of the vehicle. As a result, the respective return channel, or the oil flowing through the respective return channel, can communicate with the reservoir interior, referred to in particular as the sump interior, below the target oil level in the vertical direction of the vehicle. Alternatively, at least one of the outlet points can be arranged above the oil level of the oil in the oil sump in the installed position of the internal combustion engine in the vertical direction of the vehicle.

[0024] In a further embodiment, the oil separation devices are arranged in a cylinder head cover which, in the installed position of the internal combustion engine, is arranged above the cylinder head of the internal combustion engine in the vertical direction of the vehicle. In other words, the oil separation devices are at least partially surrounded by the cylinder head cover. The cylinder head is arranged above the crankcase in the vertical direction of the vehicle and at least partially, in particular directly, delimits the crankcase upwards in the vertical direction of the vehicle. The cylinder head cover can in particular be referred to as a valve cover and at least partially, in particular directly, delimits the cylinder head upwards in the vertical direction of the vehicle. Because the oil separation devices are arranged in the cylinder head cover, the geodetic height difference or the distance can be particularly increased, whereby the pressure loss potential can be particularly increased.

[0025] In a further embodiment, the return channels each have at least one second longitudinal region through which the oil can flow, which is arranged upstream of the respective longitudinal region in the flow direction of the oil flowing through the return channels and which runs within the cylinder head, wherein the second longitudinal region is delimited in its circumferential direction at least partially, in particular completely circumferentially, by the cylinder head, in particular directly. In other words, at least the respective second longitudinal region of the return channels is arranged in the cylinder head, whereby the two parts of the oil can be guided or introduced from the respective oil separation device through the cylinder head into the reservoir. As a result, the two parts of the oil from the respective oil separation devices can be guided from the cylinder head cover via the cylinder head through the crankcase into the reservoir.

[0026] In a further embodiment, the respective return channel is produced by drilling and / or casting. In other words, the respective length region and / or the respective second length region is produced by drilling and thus designed as a respective bore and / or is produced by casting and thus cast. In other words, the respective return channel can be machined by drilling and / or the respective return channel can be cast.The respective return channel, which is designed as a bore, can be manufactured, for example, by means of two intersecting bores, wherein a first of the bores can start from the cylinder head, which can in particular be referred to as a bore coming from a cover surface, and a second of the bores can start from the reservoir side, which can in particular be referred to as a bore coming from the reservoir side or oil pan side. The casting of the respective return channels is preferably carried out using at least one core. By drilling or casting, the respective return channel can be manufactured particularly cost-effectively and / or particularly precisely. The respective cross-sections of the return channels can be designed with different sizes depending on requirements and manufacturing possibilities. At least one sealing element can be installed between the reservoir and the crankcase, in particular the housing wall.In other words, the sealing element can be arranged between the reservoir and the crankcase, in particular the housing wall, by means of which the reservoir or the respective return channel can be kept particularly tight.

[0027] A second aspect of the invention relates to a motor vehicle having an internal combustion engine 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. The motor vehicle according to the invention is preferably designed as a motor vehicle, in particular as a passenger car, commercial vehicle, or truck, or as a passenger bus or motorcycle.

[0028] A third aspect of the invention relates to a method for operating an internal combustion engine for a motor vehicle according to the first aspect of the invention, said engine having a crankcase and at least two separately formed oil separator devices. Advantages and advantageous embodiments of the first aspect and the second aspect of the invention are to be regarded as advantages and advantageous embodiments of the third aspect of the invention, and vice versa.

[0029] In the method according to the invention, oil is separated from a blow-by gas discharged from the crankcase and fed to the oil separation devices by means of the oil separation devices. By means of a return device through which the oil separated by the oil separation devices can flow, the oil separated from the blow-by gas by the oil separation devices is guided or introduced from the oil separation devices into a reservoir. The reservoir is preferably arranged in the installed position of the internal combustion engine in the vertical direction of the vehicle below the oil separation devices. The reservoir is preferably designed as an oil pan in which the oil introduced into the oil pan is collected.

[0030] In order to be able to separate the oil particularly advantageously from the blow-by gas, it is provided according to the invention that the return device has at least one first return channel through which a first part of the oil separated from the blow-by gas by means of a first of the oil separation devices can flow, via which the first part of the separated oil is guided from the first oil separation device into the reservoir, and at least one second return channel which is at least partially spaced or separated from the first return channel and through which a second part of the oil separated from the blow-by gas by means of the second oil separation device can flow, via which the second part of the separated oil is guided from the second oil separation device into the reservoir.

[0031] Further features of the invention emerge from the claims, the figures, and the description of the figures. 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 combination, but also in other combinations or on their own.

[0032] The invention will now be explained in more detail using a preferred embodiment and with reference to the drawings. They show: Fig. 1 shows a schematic partial sectional view of an internal combustion engine according to the invention in a perspective view; and Fig. 2 shows a schematic partial sectional view of an internal combustion engine according to the invention in a side perspective view; and Fig. 3 shows a schematic partial sectional view of an internal combustion engine according to the invention in a front perspective view; and Fig. 4 shows a schematic partial sectional view of an internal combustion engine according to the invention in a front perspective view.

[0033] In the figures, identical or functionally identical elements are provided with the same reference numerals.

[0034] Fig. 1 shows in a schematic partial sectional view an internal combustion engine 1 for a motor vehicle 2 in a perspective view and Fig. 2 shows in a schematic partial sectional view the internal combustion engine 1 in a side perspective view and Fig. 3 shows a schematic partial sectional view of the internal combustion engine 1 in a front perspective view. The motor vehicle 2 is preferably designed as a motor vehicle, in particular as a passenger car, commercial vehicle, or truck. The internal combustion engine 1 comprises an output shaft, designed in particular as a crankshaft, via which the motor vehicle 2 can be driven by the internal combustion engine 1.

[0035] The internal combustion engine 1 has at least one crankcase 3, particularly referred to as a cylinder crankcase, which at least partially delimits at least one cylinder 4 and a crank chamber 5 of the internal combustion engine 1, wherein the internal combustion engine 1 shown in the exemplary embodiment comprises six cylinders 4. Each cylinder 4 has a cylinder wall 6, which in each case partially delimits a combustion chamber 7. A piston is arranged in each cylinder 4, which is translationally movable relative to the cylinder wall 6. The internal combustion engine 1 has an intake tract through which air can flow and an exhaust tract through which an exhaust gas from the internal combustion engine 1 can flow. The air, particularly referred to as fresh air, can be supplied to the combustion chamber 7 via the intake tract, and the exhaust gas can be discharged from the combustion chamber 7 via the exhaust tract.In an activated state of the internal combustion engine, combustion processes, in particular referred to as combustion, take place in the respective combustion chamber 7, wherein a fuel-air mixture comprising the fresh air is burned, resulting in the exhaust gas of the internal combustion engine 1.

[0036] In particular, in the activated state of the internal combustion engine 1, a gas, in particular the exhaust gas, can pass from the respective combustion chamber 7, in particular through a gap which is at least partially formed by the respective piston and the respective cylinder wall 6, into the crankcase 3 or the crank chamber 5, wherein the gas passing from the respective combustion chamber 7 into the crankcase 3 or the crank chamber 5 and located in the crank chamber 5 can be referred to in particular as blow-by gas. The internal combustion engine 1 has at least two, in particular separately formed, oil separation devices 8, 9, by means of which oil can be separated from the blow-by gas discharged from the crankcase 3 or the crank chamber 5 and supplied to the oil separation devices 8, 9. The oil separation devices 8, 9 are in the Figuren 1 and 3schematically sketched. The internal combustion engine 1 comprises a return device 10 through which the oil separated by means of the oil separation devices 8, 9 can flow, via which the oil separated from the blow-by gas by means of the oil separation devices 8, 9 can be guided or introduced from the oil separation devices 8, 9 into a reservoir 11. The reservoir 11 can in particular be designed as an oil pan and be provided for collecting the oil. The reservoir 11 is preferably arranged in the installed position of the internal combustion engine in the vehicle vertical direction 12 below the oil separation devices 8, 9 in the crankcase 3 or the crank chamber 5 or in the vehicle vertical direction 12 below the crankcase 3. The internal combustion engine 1, in its fully manufactured state, assumes the installed position in the motor vehicle 2 in a fully manufactured state of the motor vehicle 2. The reservoir 11 is in Fig. 4 , which shows a schematic partial sectional view of the internal combustion engine 1 in a front perspective view. In a designated flow direction 12a, the oil flowing through the return device 10 flows from the respective oil separation device 8, 9 to the reservoir 11.

[0037] In order to be able to separate the oil from the blow-by gas in a particularly advantageous manner, the return device 10 has at least one first return channel 14 through which a first part 13 of the oil separated from the blow-by gas by means of a first of the oil separation devices 8 can flow, via which the first part 13 of the separated oil can be guided from the first oil separation device 8 into the reservoir 11, and at least one second return channel 16 which is at least partially spaced or separated from the first return channel 14 and through which a second part 15 of the oil separated from the blow-by gas by means of the second oil separation device 9 can flow, via which the second part 15 of the separated oil can be guided from the second oil separation device 9 into the reservoir 11.

[0038] As a result, a respective geodetic height difference or a respective distance 17, 18 in the vehicle's vertical direction 12 between the respective oil separation device 8, 9 and the reservoir 11 can be particularly increased. This can be understood in particular as the following: The respective distance 17, 18 runs in the vehicle's vertical direction 12, for example, between a respective first point 8a, 9a of the respective oil separation device 8, 9 and a second point 11a of the reservoir 11. The respective first point 8a, 9a is arranged, for example, in a respective outlet opening of the respective oil separation device 8, 9 and the second point 11a is arranged in the reservoir 11. The respective oil separation device 8, 9 is fluidically connected to the return device 10 via the respective outlet opening. The respective first point 8a, 9a is preferably a lowest point of the respective outlet opening in the vehicle's vertical direction 12.Because the respective distance 17, 18 can be particularly increased, the respective pressure loss potential of the respective oil separation device 8, 9 can be particularly increased. This allows, on the one hand, a filtration efficiency of the respective oil separation device 8, 9 to be particularly increased, and, on the other hand, it can be prevented that oil located in the reservoir 11 flows upwards through the return device 10, in particular the respective return channel 14, 16, in the vehicle's vertical direction 12 and thus counter to the intended flow direction 12a to the respective oil separation device 8, 9. This allows, on the other hand, the filtration efficiency of the respective oil separation device 8, 9 to be particularly increased, and the introduction of the returned oil into the intake tract can be prevented, whereby pollutant emissions from the internal combustion engine 1 can be kept particularly low.

[0039] Preferably, in the installed position of the internal combustion engine 1 in the motor vehicle 2, the oil separation devices 8, 9 are each equidistant from the reservoir 11 in the vehicle's vertical direction 12. In other words, a first of the distances 17 between the first oil separation device 8 and the reservoir 11 is equal to the second of the distances 18 between the second oil separation device 9 and the reservoir 11. As a result, both geodetic height differences or both distances 17, 18 can be significantly increased, whereby both oil separation devices 8, 9 can have a particularly high pressure loss potential.

[0040] In a further embodiment, the return channels 14, 16 each have at least one longitudinal region 20, 21 through which the oil can flow and which runs within a housing wall 19 of the crankcase 3, which is delimited in its respective circumferential direction 22, 23 at least partially, in particular completely circumferentially, by the housing wall 19, in particular directly. The first return channel 14 or the longitudinal region 20, 21 of the first return channel 14 is arranged on the inlet side of the crankcase 3. The second return channel 16 or the longitudinal region 20, 21 of the second return channel 16 is arranged on the inlet side of the crankcase 3.The inlet-side or outlet-side arrangement can be understood in particular as follows: With reference to an imaginary center plane of the cylinders 4 extending in the vertical direction 12 of the vehicle and in the longitudinal direction of the output shaft, a first side of the center plane can be referred to as the inlet-side, with the air flowing through the intake tract being guided to the combustion chambers 7 via the first side, and a second side of the center plane opposite the first side can be referred to as the exhaust-side, with the exhaust gas flowing through the exhaust tract being discharged from the combustion chambers 7 via the second side. Fig. 2 The partial sectional view shown is a partial sectional view of the inlet side.

[0041] Preferably, the first oil separator 8 is designed as a partial-load oil separator, and the second oil separator 9 is designed as a full-load oil separator. As a result, the first return channel 14 is referred to as a partial-load separation channel, and the second return channel 16 is referred to as a full-load separation channel.

[0042] The internal combustion engine 1 comprises a cylinder head 25, which, in the installed position of the internal combustion engine 1 in the motor vehicle 2, is arranged above the crankcase 3. The oil separation devices 8, 9 are preferably arranged in a cylinder head cover 24, which, in the installed position of the internal combustion engine 1 in the motor vehicle 2, is arranged above the cylinder head 25 of the internal combustion engine 1 in the vehicle's vertical direction 12. The cylinder head cover 24 can in particular be referred to as a valve cover and at least partially, in particular directly, delimits the cylinder head 25 upwards in the vehicle's vertical direction 12.In a further embodiment, the return channels 14, 16 each have at least one second longitudinal region 26, 27 through which the oil can flow, which is arranged upstream of the respective longitudinal region 20, 21 in the flow direction 12a of the oil flowing through the return channels 14, 16 and which runs within the cylinder head 25. The respective second longitudinal region 26, 27 is delimited in its respective circumferential direction 28, 29 at least partially, in particular completely circumferentially, by the cylinder head 25, in particular directly. As a result, the oil can be guided from the respective oil separation device 8, 9 through the cylinder head 25 and the crankcase 3 into the reservoir 11. In particular, the distances 17, 18 can be increased particularly because the oil separation devices 8, 9 are arranged in the cylinder head cover 24.

[0043] In a further embodiment, the internal combustion engine 1 comprises respective opening points 30, 31, at which the return channels 14, 16 open into at least one receiving area 32 directly delimited by the reservoir 11, in which the oil can be received. As a result, the oil flowing through the return channels 14, 16 can be discharged or led out of the respective return channel 14, 16 via the respective opening points 30, 31 and introduced into the reservoir 11 or the receiving area 32. The opening points 30, 31 are in the Fig. 4sketched schematically by way of example. Preferably, the return channels 14, 16 each have at least one third longitudinal region 33 through which the oil can flow, arranged downstream of the respective longitudinal region 20, 21 in the flow direction 12a of the oil flowing through the return channels 14, 16, which extends within a reservoir wall 34 of the reservoir 11, wherein the third longitudinal region 33 is delimited in its circumferential direction at least partially, in particular completely circumferentially, by the reservoir wall 34, in particular directly.

[0044] In a further embodiment, at least one of the outlet points 30, 31 is arranged, in the installed position of the internal combustion engine 1 in the motor vehicle 2, in the vehicle vertical direction 12 below an oil level 35 of the oil located in the reservoir 11, in particular referred to as the oil level. As a result, the reservoir 11 can assume the function of a siphon, in particular referred to as an oil siphon, whereby a corresponding oil siphon formed separately from the reservoir 11 can be omitted, wherein the oil collected in the reservoir 11 can flow out of the reservoir 11, for example, when a defined fill level of the reservoir 11 is exceeded, in particular laterally or laterally downwards in the vehicle vertical direction. In other words, the oil siphon can be relocated into the reservoir 11. In other words, the third longitudinal region 33 can extend the respective return channel 14, 16 in the vehicle vertical direction 12 to below the oil level 35.Alternatively, at least one of the outlet points 30, 31 can be arranged above the oil level 35 in the installation position of the internal combustion engine 1 in the vehicle vertical direction 12.

[0045] Preferably, the respective return channel 14, 16, in particular at least one of the respective length regions 20, 21, 26, 27, 33, is produced by drilling and / or casting. This allows the internal combustion engine 1, in particular the respective return channel 14, 16, to be produced particularly advantageously and particularly cost-effectively. In at least one of the respective return channels 14, 16, in particular in the respective length region 20, 21, at least one valve device 36, particularly referred to as a check valve, can be arranged, by means of which a respective mass flow of the oil flowing through the respective return channel 14, 16 can be adjusted. This makes it particularly advantageous to prevent, for example, a backflow of oil from the reservoir 11 through the respective return channel 14, 16 to the respective oil separation device 8, 9, running counter to the flow direction 12a. List of reference symbols

[0046] 1 Internal combustion engine 2 Motor vehicle 3 Crankcase 4 Cylinder 5 Crankchamber 6 Cylinder wall 7 Combustion chamber 8 First oil separator device 8 a First point 9 Second oil separator device 9 a First point 10 Return device 11 Reservoir 11 a Second point 12 Vehicle vertical direction 12 a Flow direction 13 First part 14 First return channel 15 z Second part 16 Second return channel 17 First distance 18 z Second distance 19 Housing wall 20 Length range 21 Length range 22 Circumferential direction 23 Circumferential direction 24 Cylinder head cover 25 Cylinder head 26 Second length range 27 Second length range 28 Circumferential direction 29 Circumferential direction 30 First outlet point 31Second outlet point 32Receiving area 33Third length area 34Reservoir wall 35Oil level 36Valve device

Claims

1. Internal combustion engine (1) for a motor vehicle (2), having a crankcase (3), having at least two oil separation devices (8, 9), by means of which oil can be separated from blow-by gas discharged from the crankcase (3) and fed to the oil separation devices (8, 9), and having a return device (10) through which the oil separated by means of the oil separation devices (8, 9) can flow and via which the oil separated from the blow-by gas by means of the oil separation devices (8, 9) can be guided from the oil separation devices (8, 9) into a reservoir (11), wherein the return device (10) has at least one first return channel (14) which can be flowed through by a first portion (13) of the oil separated from the blow-by gas by means of a first of the oil separation devices (8) and via which the first portion (13) of the separated oil can be guided from the first oil separation device (8) into the reservoir (11), and at least one second return channel (16) which is at least partially spaced apart from the first return channel (14), which can be flowed through by a second portion (15) of the oil separated from the blow-by gas by means of the second oil separation device (9) and via which the second portion (15) of the separated oil can be guided from the second oil separation device (9) into the reservoir (11), and wherein the return channels (14, 16) each have at least one length region (20, 21) through which the oil can flow, which runs within a housing wall (19) of the crankcase (3) and which is delimited in its circumferential direction (22, 23) at least partially by the housing wall (19), and wherein respective opening points (30, 31) are provided at which the return channels (14, 16) open into a receiving region (32) which is delimited by the reservoir (11) and in which the oil can be received, characterized in that at least one of the opening points (30, 31) is arranged below an oil level (35) of the oil located in the reservoir (11) in the vertical direction (12) of the vehicle, wherein the return channels (14, 16) each have at least one length region (33) through which the oil can flow, which is arranged downstream of the respective length region (20, 21) in the flow direction (12a) of the oil flowing through the return channels (14, 16), which runs within a reservoir wall (34) of the reservoir (11) and which is delimited in its circumferential direction at least partially by the reservoir wall (34).

2. Internal combustion engine (1) according to Claim 1, characterized in that the oil separation devices (8, 9) are each spaced apart from the reservoir (11) at the same distance in the vertical direction (12) of the vehicle.

3. Internal combustion engine (1) according to Claim 1 or 2, characterized in that the oil separation devices (8, 9) are arranged in a cylinder head cover (24) which is arranged above a cylinder head (25) of the internal combustion engine (1) in the vertical direction (12) of the vehicle.

4. Internal combustion engine (1) according to Claim 3, characterized in that the return channels (14, 16) each have at least one second length region (26, 27) through which the oil can flow, which is arranged upstream of the respective length region (20, 21) in the flow direction (12a) of the oil flowing through the return channels (14, 16) and which runs within the cylinder head (25), wherein the second length region (26, 27) is delimited in its circumferential direction (28, 29) at least partially by the cylinder head (25).

5. Internal combustion engine (1) according to one of the preceding claims, characterized in that the respective return channel (14, 16) is produced by means of drilling and / or by means of casting.

6. Motor vehicle (2) having an internal combustion engine (1) according to one of the preceding claims.

7. Method for operating an internal combustion engine (1) according to one of Claims 1 to 5.