Multi-cylinder internal combustion engine for a motor vehicle

Abstract

Multi-cylinder internal combustion engine (1) for a motor vehicle (2), comprising at least the following components: - a first cylinder (3) with a first piston (4) in which a first ignition can be performed for starting; and - a second cylinder (5) with a second piston (6) in which a second ignition can be performed for starting, characterized in that the blow-by rate is greater than that of the first cylinder (3) by means of a design adaptation of the second cylinder (5).

Description

[0001] The invention relates to a multi-cylinder internal combustion engine for a motor vehicle, as well as a motor vehicle with such a multi-cylinder internal combustion engine.

[0002] In industrial practice, the starting torque of internal combustion engines in motor vehicles is usually overcome by a separate starter motor, which is typically an electric drive. This starting torque is composed of various components, including the engine's moment of inertia, frictional torque, and compression torque, which reduce the engine's acceleration to a starting speed. The compression torque arises from the compression of the cylinder charge in a cylinder during the compression stroke. Only when the starting torque of the internal combustion engine is exceeded is the engine's starting speed reached, allowing it to be started.

[0003] A so-called direct start is also known from the prior art, in which the initial torque is overcome by means of multiple ignitions in multiple cylinders. Thus, no starter motor is required to start the internal combustion engine, and the engine is self-starting. In a direct start, the engine is accelerated from its rest position solely by ignitions and the resulting combustion expansion. The first ignition occurs in a first cylinder, which is in its expansion stroke, and sets the engine in initial rotation. A second ignition then follows in another cylinder, which is in its compression stroke during the first ignition. Consequently, starting the internal combustion engine takes some time due to the high initial torque.Due to the time delay involved in starting the internal combustion engine, direct starting is only feasible to a very limited extent in hybrid vehicles. Therefore, hybrid vehicles are equipped with starters to start the internal combustion engine, and these systems usually incorporate an existing electric drive motor for this purpose. An electric drive motor, also known as a traction motor, is designed to generate torque for the sole (purely electric) or supplementary (hybrid) propulsion of the vehicle.

[0004] If the electric drive motor (as a starter) is also a component of a hybrid vehicle's hybrid module, the starting torque for the combustion engine is withheld during operation. Therefore, the full power of the electric drive motor is not available in a hybrid vehicle, significantly reducing the overall efficiency of the hybrid vehicle.

[0005] DE 10 2022 109 743 B3 discloses a method for preparing to start an internal combustion engine, minimizing resistance torque during starting. The method includes measuring the cylinder pressure of the internal combustion engine's cylinders during towing and / or driving operation of the vehicle. To optimally overcome resistance torque, the cylinder suitable for direct starting is the cylinder located before the cylinder with the lowest cylinder pressure in the firing order. Therefore, with a firing order of 1-3-4-2 and cylinder 3 having the lowest pressure, cylinder 1 is designated as the direct starting cylinder, which is to be fired first during a subsequent start or restart of the internal combustion engine.

[0006] DE 10 2011 006 288 A1 discloses a method for starting an internal combustion engine without a starter motor, wherein some of the cylinders of the internal combustion engine are designed as decompressible cylinders. The method includes adjusting the end position of a crankshaft. To ensure a starter-free starting process of the internal combustion engine, an air / fuel mixture is injected and ignited in a cylinder of the internal combustion engine that is in a combustion stroke while the engine is stationary. To prevent the rotational energy generated from dissipating too quickly, it is ensured during the first and possibly subsequent ignition cycles that compression is excluded in the cylinder in the compression stroke. This is achieved by keeping at least one of the intake and exhaust valves of this cylinder open, thereby preventing a counter-torque acting against the rotation of the crankshaft.

[0007] DE 10 2014 205 349 A1 discloses a method for the direct starting of an internal combustion engine, whereby the expansion loss is reduced by adjustable valve timing. The method comprises switching off the internal combustion engine, determining the shutdown positions, setting the exhaust valve timing to a second value, igniting an air / fuel mixture, and readjusting the exhaust valve timing. The exhaust valve timing of the internal combustion engine can be optimized using this second value. Blow-by, the engine's moment of inertia, and / or its number of cylinders or firing interval are taken into account in a correction of the second exhaust valve timing value.Once it has been detected that an exhaust valve of the first cylinder in firing order has closed, and before an air / fuel mixture is ignited in the second cylinder of the internal combustion engine in firing order, the exhaust valve timing is set to the first value, which corresponds to the standard position of an exhaust camshaft.

[0008] Based on this, the present invention aims to overcome, at least partially, the disadvantages known from the prior art. The features of the invention are defined in the independent claims, for which advantageous embodiments are shown in the dependent claims. The features of the claims can be combined in any technically meaningful way, whereby the explanations in the following description and features from the figures, which comprise supplementary embodiments of the invention, can also be used.

[0009] The invention relates to a multi-cylinder internal combustion engine for a motor vehicle, comprising at least the following components: - a first cylinder with a first piston, in which a first ignition can be performed for starting; and - a second cylinder with a second piston, in which a second ignition can be performed for starting.

[0010] The multi-cylinder internal combustion engine is characterized primarily by the fact that the blow-by rate of the second cylinder is greater than that of the first cylinder, achieved through a design modification.

[0011] Unless explicitly stated otherwise, ordinal numbers used in the preceding and following descriptions serve solely for unambiguous differentiation and do not indicate any order or ranking of the components referred to. An ordinal number greater than one does not necessarily imply the presence of another such component.

[0012] To generate torque through ignition, a multi-cylinder internal combustion engine comprises multiple cylinders, each with a piston. This piston is reciprocating within the cylinder and is connected to a crankshaft to convert its translational motion into rotational motion (torque). The crankshaft is designed to transmit this torque to a consumer. A fuel-air mixture can be introduced into each cylinder. This (approximately stoichiometric) fuel-air mixture is compressible by the corresponding piston. Specifically, the first piston experiences a translational force opposite to its compression motion as a result of combustion expansion of the fuel-air mixture following (external or auto-)ignition, and transmits this resulting expansion force to the crankshaft.At least two of the pistons, preferably all pistons, have different crank angles, such that these pistons are in different translational positions within their respective cylinders, preferably without two pistons being at the same dead center (i.e., the endpoints) of their translational movement simultaneously. Preferably, at least one of the pistons performs a (power-consuming) compression stroke when a piston performs a (power-releasing) expansion stroke as a result of ignition.

[0013] With a suitable crankshaft angle, it is known that a multi-cylinder internal combustion engine can be (self-)started by means of an ignition (the first in the firing order) and the subsequent torque transmission, i.e., without an external starter. It should be noted that here the cylinders are designated with ordinal numbers according to their firing order and not according to a spatial arrangement. The first ignition therefore always occurs in the first cylinder, by definition. It should be noted that the firing order is usually determined by the design or the existing crankshaft angles. However, there are also configurations in which the firing order is variable and / or an ignition is omitted during operation. For example, a piston can be decoupled and / or (preferably without compression) dragged along. In one embodiment, the self-starting firing order differs from the firing order during torque-delivering operation.

[0014] Furthermore, the multi-cylinder internal combustion engine includes a second cylinder in which a second piston is located. Like the first piston, the second piston is designed to compress a fuel-air mixture and transmit power to a crankshaft, generating torque as a result of the second ignition (in the firing sequence) within the second cylinder. The second piston is connected to the first piston in such a way that, during the first ignition in the first cylinder and the subsequent movement of the first piston, the second piston is also moved, thus moving the second piston from its initial position and executing a compression stroke in preparation for the second ignition.Thus, by means of the first ignition and the subsequent second ignition, a rotation of the crankshaft and therefore of the pistons can be accelerated, so that the multi-cylinder internal combustion engine can be accelerated to a starting speed.

[0015] During the combustion of the fuel-air mixture within a cylinder, so-called blow-by gases are emitted. These gases do not contribute to the translational kinetic energy but escape through gaps between the cylinder and the piston. Blow-by gases include (though not all of the following are necessarily present) residues of engine oil, unburned fuel residues (hydrocarbons in a multi-cylinder internal combustion engine using, for example, natural gas, gasoline, or diesel fuel), and nitrogen oxides. Blow-by gases are gases that do not follow the intended gas passage in the multi-cylinder internal combustion engine during combustion. They occur as a result of an unavoidable leakage within the combustion process. The blow-by rate represents the ratio of blow-by gases to the exhaust gases.The blow-by rate can therefore be understood as a pressure loss or decompression within a cylinder over a combustion cycle and thus influences the compression torque. It should be noted that blow-by gases do not escape from the multi-cylinder internal combustion engine, but are generally fed back into the fuel-air mixture of the next charge via exhaust gas recirculation. Alternatively, blow-by gases are combusted in the exhaust system (fuel residues are oxidized) or reduced by means of filtration and / or (for example, so-called selective or three-way) catalysis, for example (in the case of diesel fuels, with the help of externally supplied ammonia).

[0016] It is proposed here that the blow-by rate of the second cylinder be higher than the blow-by rate of the first cylinder. The blow-by rate can be adjusted, for example, by means of a design modification of the second cylinder. In one embodiment, the blow-by rate is adjustable by means of a corresponding fit between the second cylinder and the corresponding second piston, such that a predefined gap is arranged between the wall of the second cylinder and the second piston.

[0017] In an alternative embodiment, the blow-by rate is achieved by means of multiple seals on the piston, allowing a predefined blow-by rate to be set in the second cylinder. Alternatively or additionally, the seals are designed to be temperature-sensitive, expanding at a predefined temperature and thus reducing the blow-by rate during operation, i.e., after numerous ignitions in the cylinder. This allows for an increased blow-by rate in a cold cylinder, for example, if the engine has not been started for some time. In another embodiment, the gap between the seal and the cylinder wall, and consequently the leakage, varies depending on the crank angle, i.e., the translational position in the cylinder. In this case, the cylinder wall (at least partially, relative to a rotational axis) is designed to expand radially in a suitable section.In many applications, the leakage is designed to be constant, and the leakage flow increases due to the intrinsic (significant) pressure increase over the course of the compression stroke. Alternatively or additionally, the leakage flow is designed to be constant or even decreasing in at least one part of the compression stroke.

[0018] It should be noted that the blow-by rate is calculated as the time-integrated leakage flow (relative to the cylinder filling). The point at which the greatest leakage flow occurs during the compression stroke is irrelevant for most applications. To further increase efficiency, the leakage flow rate is designed to depend on the crank angle of the piston (or multiple pistons) performing the expansion stroke. The aim here is to maximize the acceleration of the second piston performing the compression stroke, so that the top dead center (maximum compression) is overcome with greater reliability due to the inertia of the second piston.

[0019] This makes a direct start (i.e., self-start) of a multi-cylinder internal combustion engine possible even under difficult conditions, such as extreme cold. For example, during a long city drive in an electrified vehicle that operates purely electrically within the city, the multi-cylinder internal combustion engine does not start. If a traction battery of the hybrid module is nearly depleted, the multi-cylinder internal combustion engine starts. Due to the low temperature of the multi-cylinder internal combustion engine, the increased blow-by rate at least partially compensates for the resistance of, for example, cold (highly viscous) lubricant, thus enabling a direct start of the multi-cylinder internal combustion engine.In one embodiment, a direct start is not possible, but a resistance torque is reduced, thus reducing the starting torque and therefore requiring a (significantly) reduced torque to be provided by the starter and / or a hybrid module.

[0020] Due to the set blow-by rate, the pressure loss or decompression within the second cylinder is greater than the pressure loss or decompression within the first cylinder. Therefore, the compression torque in the second cylinder decreases during the expansion torque of the first cylinder. Thus, the magnitude of the compression torque decreases with increasing blow-by rate.

[0021] In a further advantageous embodiment of the multi-cylinder internal combustion engine, it is proposed that a third cylinder with a third piston, in which a third ignition can be performed for starting, preferably with a blow-by rate of the third cylinder being greater than that of the first cylinder, where the blow-by rate of the third cylinder is particularly preferred to be smaller than that of the second cylinder.

[0022] It is further proposed here that the multi-cylinder internal combustion engine includes a third cylinder with a third piston, wherein the third cylinder is configured for (repeated) starting of the multi-cylinder internal combustion engine by means of a third ignition in the firing sequence. In one embodiment, the blow-by rate of the third cylinder is less than or equal to the blow-by rate of the first cylinder. For example, in this embodiment, the third cylinder with its third piston is identical in construction to the first cylinder.

[0023] In a preferred embodiment, the blow-by rate of the third cylinder is greater than that of the first cylinder, so that, due to the higher blow-by rate, the compression torque in the third cylinder is lower, thus simplifying the starting of the multi-cylinder internal combustion engine. In this embodiment, the third cylinder and the third piston are, for example, identical in design to, or in any form whatsoever, the second cylinder and the second piston.

[0024] In a particularly preferred embodiment, the blow-by rate of the third cylinder is lower than the blow-by rate of the second cylinder, but still higher than the blow-by rate of the first cylinder. In this embodiment, the compression torque is highest in the first cylinder due to the blow-by rates, lowest in the second cylinder due to the increased blow-by rate, and (somewhat) higher again in the third cylinder. It should be noted that the second ignition (in terms of firing order) must occur in the cylinder where the next compression stroke is initiated by the first ignition in the first cylinder. The first ignition, and the resulting torque, is still largely consumed by the resistance torque resulting from inertia.The second ignition, and the resulting torque, is now subjected to a lower resistance torque because the pistons and crankshaft are already rotating, although not yet at a stable idle speed, provided the starting process is not yet complete. This means that further acceleration to a higher speed is necessary, so a resistance torque due to inertia still exists. The third ignition (in terms of timing) must occur in the cylinder where the second ignition in the second cylinder initiates the next compression stroke. Therefore, it is not necessary to assume the same blow-by rate for the third cylinder as for the second, precisely because a larger proportion of the energy from the second ignition is available for compression in the third cylinder.In an advantageous embodiment, a larger mass of fuel-air mixture is used in the second ignition in the second cylinder compared to the first ignition in the first cylinder, resulting in a greater piston force. This is because the forces or moments opposing the piston force are already reduced, and a component load limit is only reached at a higher expansion force during the second ignition compared to the first. Consequently, it may also be advantageous to design the blow-by rate of the second cylinder to be higher than that of the third cylinder.

[0025] In a further advantageous embodiment of the multi-cylinder internal combustion engine, it is proposed that a fourth cylinder with a fourth piston, in which a fourth ignition in time can be carried out for starting, preferably with a blow-by rate of the fourth cylinder being greater than that of the first cylinder, where the blow-by rate of the fourth cylinder is particularly preferred to be smaller than that of the second cylinder and / or the third cylinder.

[0026] It is further proposed here that the multi-cylinder internal combustion engine comprises a fourth cylinder with a fourth piston, wherein the fourth cylinder is configured for (repeated) starting of the multi-cylinder internal combustion engine by means of a fourth ignition in the firing sequence. In one embodiment, the blow-by rate of the fourth cylinder is less than or equal to the blow-by rate of the first cylinder. For example, in this embodiment, the fourth cylinder with its fourth piston is identical in construction to the first cylinder.

[0027] In a preferred embodiment, the blow-by rate of the fourth cylinder is greater than the blow-by rate of the first cylinder, so that due to the higher blow-by rate, the compression torque in the fourth cylinder is lower, thus simplifying the starting of the multi-cylinder internal combustion engine. In this embodiment, the fourth cylinder is, for example, designed to be identical in shape to, or in the same shape as, the second and / or third cylinder.

[0028] In a particularly preferred embodiment, the blow-by rate of the fourth cylinder is lower than the blow-by rate of the second and / or third cylinder, but still higher than the blow-by rate of the first cylinder. In this embodiment, the compression torque is highest in the first cylinder due to the blow-by rates, lowest in the second cylinder due to the increased blow-by rate, and (somewhat) higher again in the third and / or fourth cylinder. Reference is made here to the explanation above, whereby, in the firing order, each subsequent ignition is driven by the expansion force from the preceding cylinder, and with increasing engine speed, an increasing torque is available for compression. A blow-by rate of the subsequent cylinders that decreases from the second is therefore particularly advantageous.

[0029] In an advantageous embodiment of the multi-cylinder internal combustion engine, it is further proposed that the different blow-by rates of the cylinders differ from each other by a minimum of 5% to a maximum of 20%.

[0030] Because blow-by rates are ratios between blow-by gases and regular combustion gases, only the relative deviation of the different blow-by rates in the cylinders is given here. As described above, the blow-by rate of the first cylinder is the lowest and can therefore be considered the baseline. The highest deviation in blow-by rates is found in the second cylinder. It should be noted again that the cylinder order refers only to the chronological sequence of ignitions (and possibly only during direct starts) in the cylinders, and not to their spatial arrangement within the multi-cylinder internal combustion engine. Thus, the deviation of the second cylinder's blow-by rate from that of the first can be up to 20%.The remaining blow-by rates range from a minimum deviation of 5% to a maximum deviation of 20%. It should be noted that the blow-by rate is preferably measured in mass percent, which, due to the desired accuracy regarding a stoichiometric (i.e., also potentially substoichiometric or superstoichiometric) fuel-air composition in the cylinders, is usually known with sufficient precision.

[0031] It should be noted that a multi-cylinder internal combustion engine can also have more than four cylinders, whereby in one embodiment four ignitions with the corresponding blow-by rates in the cylinders are sufficient to accelerate the multi-cylinder internal combustion engine to a starting speed. In an alternative embodiment, more than four cylinders or ignitions are required to accelerate the multi-cylinder internal combustion engine to the predetermined starting speed. This results in a distribution of the blow-by rates across a number of cylinders greater than four.

[0032] According to another aspect, an electrified motor vehicle is proposed, featuring at least one electric drive motor, a multi-cylinder internal combustion engine according to an embodiment as described above, and at least one drive wheel that can be driven by the multi-cylinder internal combustion engine and the electric drive motor, wherein the multi-cylinder internal combustion engine is self-starting, and / or wherein starting the multi-cylinder internal combustion engine can be supported by the electric drive motors, and preferably simultaneously with starting the multi-cylinder internal combustion engine, drive power for the electrified motor vehicle can be provided by the starting electric drive motor.

[0033] The electrified motor vehicle comprises at least one electric drive motor and at least one multi-cylinder internal combustion engine as described above. The multi-cylinder internal combustion engine and the electric drive motor can be operated simultaneously in at least one operating state and separately in other operating states. The drive wheels transmit the generated torque to the ground and propel the electrified motor vehicle. For example, if the traction battery of the electric drive motor is nearly depleted, in one embodiment the electric drive motor transmits the necessary starting torque to the multi-cylinder internal combustion engine, causing it to start and provide the required drive power.Alternatively or additionally, when the driver demands high torque (for example, accelerator pedal in full throttle position), the multi-cylinder internal combustion engine is used to deliver torque and is towed for this purpose. Due to the blow-by rates within the cylinders of the multi-cylinder internal combustion engine described above, a reduction in the towing torque for the multi-cylinder internal combustion engine is possible, so that a towing torque permanently held back by the electric drive motor is at least partially available during purely electric and / or combined driving.

[0034] In an alternative embodiment, the multi-cylinder internal combustion engine is designed to be self-starting, so that, due to the increased blow-by rates, self-starting of the multi-cylinder internal combustion engine is possible under all or most boundary conditions without externally overcoming the starting torque. Thus, in this embodiment, the multi-cylinder internal combustion engine does not require a starter motor. This means that in an electrified vehicle, no starting torque needs to be continuously withheld by the electric drive motor, and the full electric drive power is available in conjunction with the drive power of the multi-cylinder internal combustion engine during operation.

[0035] In an alternative embodiment, direct starting is not possible under all or extreme boundary conditions; however, the starting torque is then significantly reduced by the increased blow-by rates of at least one of the subsequent cylinders in the firing order, and thus the starter and / or the electric drive motor must provide a significantly reduced torque to guarantee starting capability. The starter and / or the electric drive motor can then be designed to be smaller or less powerful for the same performance.

[0036] According to a further aspect, a motor vehicle is proposed comprising a multi-cylinder internal combustion engine according to an embodiment as described above and at least one drive wheel that can be driven by the multi-cylinder internal combustion engine. the multi-cylinder internal combustion engine is self-starting.

[0037] The motor vehicle comprises a multi-cylinder internal combustion engine as described above, wherein the multi-cylinder internal combustion engine is configured to generate torque. This torque is transmittable to at least one of the drive wheels, which are configured to propel the motor vehicle. Furthermore, due to the blow-by rates described above from at least one of the subsequent cylinders in the firing order of the multi-cylinder internal combustion engine, a reduction in the starting torque is achieved, enabling the multi-cylinder internal combustion engine to be self-starting and thus capable of starting without a starter motor. The self-start capability of the multi-cylinder internal combustion engine allows for a reduction in the weight of the motor vehicle's drivetrain.

[0038] In an alternative embodiment, direct starting is not possible under all or extreme boundary conditions; however, the starting torque is then significantly reduced by the increased blow-by rates of at least one of the subsequent cylinders in the firing order, and thus the starter motor must provide a significantly reduced torque to guarantee starting capability. The starter motor can then be smaller or less powerful.

[0039] The invention described above is explained in detail below against the relevant technical background with reference to the accompanying drawings, which show preferred embodiments. The invention is in no way limited by the purely schematic drawings, although it should be noted that the drawings are not dimensionally accurate and are not suitable for defining size relationships. It is illustrated in Fig. 1. A multi-cylinder internal combustion engine in a schematic sectional view; and Fig. 2 an electrified motor vehicle in a perspective view.

[0040] In Fig. Figure 1 shows a multi-cylinder internal combustion engine 1 in a schematic sectional view. To generate torque through ignition within the cylinder, the multi-cylinder internal combustion engine 1 comprises a plurality of cylinders 3, 5, 7, 9, each with a piston 4, 6, 8, 10. These pistons are reciprocating within the cylinders 3, 5, 7, 9 and are connected to a crankshaft (not shown) to convert translational (force) motion into rotational motion (torque). A fuel-air mixture can be introduced into the respective cylinders 3, 5, 7, 9 (shown above the pistons 4, 6, 8, 10), where it expands upon ignition, causing the pistons 4, 6, 8, 10 to move translationally (downwards, as shown).In the illustrated example, all pistons 4, 6, 8, and 10 have different crank angles, so that the pistons 4, 6, 8, and 10 are in different translational positions in their respective cylinders 3, 5, 7, and 9. With a suitable crank angle, it is known that a multi-cylinder internal combustion engine 1 can be (self-)started by means of an ignition (the first in the firing sequence 13, 14) and the subsequent torque transmission, i.e., without an external starter. The other pistons 6, 8, and 10 are connected to the first piston 4 in such a way that when the first ignition occurs in the first cylinder 3 and the first piston 4 moves, the other pistons 6, 8, and 10 are also moved. Thus, the second piston 6 is moved from its initial position and, performing a compression stroke (as shown, upwards), is aligned for a second ignition.Thus, by means of the first ignition and the subsequent second ignition, a rotation of the crankshaft and therefore of the pistons 4, 6, 8, 10 can be accelerated, so that the multi-cylinder internal combustion engine 1 can be accelerated to a starting speed.

[0041] It should be noted that here the four cylinders 3, 5, 7, 9 are designated with ordinal numbers and reference symbols according to their firing order 13, 14, and not according to a spatial arrangement. The first ignition therefore always occurs in the first cylinder 3, the second ignition in the second cylinder 5, and so on. As shown, a first firing order 13 is depicted above the figure and a second firing order 14 below, where (purely optionally) in both cases the first cylinder 3 with its first piston 4 is located at the left end of the multi-cylinder internal combustion engine 1, and the third cylinder 7 with its third piston 8 is located at the right end. In the first firing order 13, as shown, the fourth cylinder 9 with its fourth piston 10 is located to the right of the first cylinder 3, and the second cylinder 5 with its second piston 6 is located to the right of the fourth cylinder 9.In the second firing order 14, the fourth cylinder 9 and the second cylinder 5 are arranged in reverse, so as shown, to the right of the first cylinder 3 is the second cylinder 5 with the second piston 6 and then the fourth cylinder 9 with the fourth piston 10.

[0042] In this embodiment, each of the cylinders 3, 5, 7, 9 has a different blow-by rate than the other cylinders, with the blow-by rate in the first cylinder 3 being the lowest. In this embodiment, the blow-by rates are (purely optionally) set by means of differently designed seals on the pistons 4, 6, 8, 10. As shown, the pistons 4, 6, 8, 10 have three sealing rings 15, 16, 17 (designated only on the first piston 4 as a representative example) for sealing the gap between the wall of the respective cylinder 3, 5, 7, 9. Thus, the gap is sealed with a predetermined sealing effect, and blow-by gases escape, taking into account economic efficiency, smooth operation (friction), and the quantity. The differences in the blow-by rates of the individual cylinders 3, 5, 7, 9 are achieved in the illustrated embodiment by means of (exaggeratedly shown) radial shortenings of at least one of the sealing rings 15, 16, 17.

[0043] In this embodiment, the blow-by rate is highest in the second cylinder 5. Accordingly, all three sealing rings 15, 16, and 17 are shown shortened (possibly purely symbolically). Furthermore, in this embodiment, the blow-by rate (for the first firing order 13) in the third cylinder 7 is somewhat lower than in the second cylinder 5. Accordingly, the middle sealing ring 16 is not shown shortened (possibly purely symbolically). Furthermore, in this embodiment, the blow-by rate (for the first firing order 13) in the fourth cylinder 9 is again somewhat lower than in the third cylinder 7. Accordingly, only the upper sealing ring 17 is shown shortened (possibly purely symbolically).

[0044] Due to the set blow-by rates, the pressure loss or decompression within the second cylinder 5 is greater than the pressure loss or decompression within the first cylinder 3; therefore, during the expansion moment of the first cylinder 3, the compression moment opposing the crankshaft's starting motion in the second cylinder 5 is lower than conventionally.

[0045] In Fig.Figure 2 shows an electrified motor vehicle 2 in a perspective view. In this embodiment, the electrified motor vehicle 2 comprises a multi-cylinder internal combustion engine 1, an electric drive motor 11 which is supplied with voltage by means of a traction battery 18, and four drive wheels 12, wherein the drive wheels 12 are configured to propel the electrified motor vehicle 2. The electrified motor vehicle 2 includes a driver's cab 19. The electric drive motor 11 is arranged between the multi-cylinder internal combustion engine 1 and the (for example, manual) transmission 20.The torque (in this purely optional embodiment of an electrified motor vehicle 2) is further transmitted via the cardan shaft 21 to a differential 22 and thus to the rear drive wheels 12, so that the electric drive motor 11 is configured both as the sole torque source and in combination with the multi-cylinder internal combustion engine 1 for propelling the motor vehicle 2. The traction battery 18 is located in the rear of the electrified motor vehicle 2. The multi-cylinder internal combustion engine 1 is located in the front of the electrified motor vehicle 2. Additionally, in this embodiment, the electric drive motor 11 is configured as a starter for the multi-cylinder internal combustion engine 1, such that the electric drive motor 11 maintains the starting torque of the multi-cylinder internal combustion engine 1 during operation.

[0046] Due to the controlled blow-by rates within the multi-cylinder internal combustion engine 1 and the resulting (partial or complete) self-startability of the multi-cylinder internal combustion engine 1, a significantly reduced starting torque is required (blocked) or even no starting torque is necessary from the electric drive motor 11 during operation. Therefore, the electric drive motor 11 can be smaller and thus lighter, or an increase in efficiency can be achieved with (almost) the same mass of the electrified vehicle 2.

[0047] It should be noted that a motor vehicle 2 without hybrid drive, i.e. with a pure multi-cylinder internal combustion engine 1 as a drive engine, can also be designed with this blow-by rate configuration for self-starting the multi-cylinder internal combustion engine 1, preferably without a starter motor (in the case of complete self-startability).

[0048] With the blow-by rates proposed here in the multi-cylinder internal combustion engine, self-starting capability and thus a reduction in weight or an increase in the overall efficiency of a motor vehicle can be achieved. Reference symbol list 1 Multi-cylinder internal combustion engine 2 motor vehicles 3 first cylinder 4 first piston 5 second cylinder 6 second piston 7 third cylinder 8 third piston 9 fourth cylinder 10 fourth piston 11 electric drive motor 12 Drive wheel 13 first firing order 14 second firing order 15 lower sealing ring 16 middle sealing ring 17 upper sealing ring 18 traction batteries 19 Driver's cab 20 gearboxes 21 Cardan shaft 22 Differential

Claims

[1] Multi-cylinder internal combustion engine (1) for a motor vehicle (2), comprising at least the following components: - a first cylinder (3) with a first piston (4) in which a first ignition can be performed for starting; and - a second cylinder (5) with a second piston (6), in which a second ignition can be performed for starting, characterized by , that the blow-by rate is greater than that of the first cylinder (3) by means of a design modification of the second cylinder (5). [2] Multi-cylinder internal combustion engine (1) according to claim 1, wherein a third cylinder (7) with a third piston (8) in which a third ignition can be carried out for starting. [3] Multi-cylinder internal combustion engine (1) according to claim 2, where the blow-by rate of the third cylinder (7) is greater than that of the first cylinder (3), and where the blow-by rate of the third cylinder (7) is smaller than that of the second cylinder (5). [4] Multi-cylinder internal combustion engine (1) according to claim 2 or claim 3, wherein a fourth cylinder (9) with a fourth piston (10) in which a fourth ignition can be carried out for starting. [5] Multi-cylinder internal combustion engine (1) according to claim 4, where the blow-by rate of the fourth cylinder (9) is greater than that of the first cylinder (3), and where the blow-by rate of the fourth cylinder (9) is smaller than that of the second cylinder (5) and / or the third cylinder (7). [6] Multi-cylinder internal combustion engine (1) according to one of the preceding claims, wherein the different blow-by rates of the cylinders (3, 5, 7, 9) differ from each other by a minimum of 5% to a maximum of 20%. [7] Multi-cylinder internal combustion engine (1) according to one of the preceding claims, wherein the blow-by rate can be reduced by means of a plurality of seals which are designed to be temperature-sensitive such that they expand at a predefined temperature and the blow-by rate can be reduced during operation, i.e. after a plurality of ignitions in the cylinder (3,5,7,9). [8] Multi-cylinder internal combustion engine (1) according to one of the preceding claims, wherein the blow-by rate is calculated as a time-integrated leakage current, the course of the amount of the leakage flow is designed to depend on the crank angle of the piston performing the expansion stroke. [9] Electrified motor vehicle (2), comprising at least one electric drive motor (11), a multi-cylinder internal combustion engine (1) according to one of the preceding claims and at least one drive wheel (12) that can be driven by means of the multi-cylinder internal combustion engine (1) and the electric drive motor (11), wherein the multi-cylinder internal combustion engine (1) is self-starting, and / or where starting the multi-cylinder internal combustion engine (1) can be supported by the electric drive motors (11). [10] Electrified motor vehicle (2) according to claim 9, wherein a drive power for the electrified motor vehicle (2) can be provided by the starting electric drive motor (11) at the same time as the multi-cylinder internal combustion engine (1) is started.

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