Method for Operating an Internal Combustion Engine for a Motor Vehicle, and Internal Combustion Engine for a Motor Vehicle

Abstract

A method for operating an internal combustion engine of a motor vehicle having a cylinder, the combustion chamber of which is delimited in the radial direction by a cylinder wall and in the axial direction by a piston and by a combustion chamber roof. The piston has an annularly peripheral piston stage which is arranged axially recessed in the piston compared with an annularly peripheral piston crown and which merges via an annularly jet splitter contour into a piston hollow arranged axially recessed in the piston in relation to the piston stage. An injector is allocated to the cylinder and via the injector several injection jets are simultaneously injected directly into the combustion chamber in a star shape for a combustion process.

Claims

1-10. (canceled)

11. A method for operating an internal combustion engine (10) of a motor vehicle, wherein the internal combustion engine comprises: a cylinder (12) with a combustion chamber (14), wherein the combustion chamber (14) is delimited in a radial direction (18) of the cylinder (12) by a cylinder wall (16), in an axial direction (24) of the cylinder (12) on a first side by a piston (20) received translationally moveably in the cylinder (12), and in the axial direction (24) of the cylinder (12) on a second side by a combustion chamber roof (26) of the internal combustion engine (10); wherein the piston (20) has an annularly peripheral piston stage (32) which is disposed axially recessed in the piston (20) compared with an annularly peripheral piston crown (30) and which merges via an annularly peripheral jet splitter contour (34) into a piston hollow (36) disposed axially recessed in the piston (20) in relation to the piston stage (32); an injector (38) allocated to the cylinder (12), wherein via the injector first injection jets (40) are simultaneously injected directly into the combustion chamber (14) in a star shape for a combustion process, wherein the first injection jets (40) are each divided into a first subset (42) entering into the piston hollow (36), into a second subset (44) entering via the piston stage (32) into a region (B) between the piston crown (32) and the combustion chamber roof (26), and into third subsets (46) which expand starting from a respective first injection jet (40) on two sides in a peripheral direction (48) of the piston (20) in opposite directions along the piston stage (32) and collide between two adjacent first injection jets (40) inside the piston stage (32) and are deflected radially inwardly; wherein the first subset (42) forms a first combustion front and the second subset (44) forms a second combustion front, wherein the third subsets (46) respectively deflected inwardly together form a third combustion front radially inwardly into a gap (50) between the first injection jets (40), and wherein the first injection jets (40) are deflected up-jet of the jet splitter contour (34) in a direction of the piston (20) by a resulting current (58) formed at least from a swirl (52), a crushing gap current (54), and a jet current (56); wherein the first injection jets (40) are divided into the third subsets (46) by a first deflector (62) in the piston stage (32) and/or the third subsets (46) are deflected inwardly by second deflectors (62′) in the piston stage (32) from the peripheral direction (48) in the radial direction (18); wherein the first injection jets (40) are each injected with a first jet breakup (α1); wherein second injection jets (68) are injected directly into the combustion chamber (14); wherein the second injection jets (68) are each injected with a second jet breakup (α2) different from the first jet breakup (α1); wherein a fourth subset is injected by the second injection jets (68) and a fourth combustion front is formed by the fourth subsets; wherein the first jet breakup (α1) of the first injection jets (40) is smaller than the second jet breakup (α2) of the second injection jets (68); wherein the first injection jets (40) reach further into the combustion chamber (14) than the second injection jets (68) and wherein the second injection jets (68) expand in a close region of the injector (38); wherein the first injection jets (40) and the second injection jets (68) are simultaneously injected into the combustion chamber (14) in a shape of a star in relation to one another; wherein when injecting, the first injection jets (40) and the second injection jets (68) alternatingly follow on from one another in the peripheral direction (48) of the piston (10); and comprising the step of: distribution of respective injection masses between the first injection jets (40) and the second injection jets (68) such that the respective injection masses correspond to a respective available mass of combustion air in the chamber in which the respective first and second injection jets (40, 68) expand.

12. The method according to claim 11, wherein respective first jet breakups (α1) of the first injection jets (40) are a same among one another and/or respective second jet breakups (α2) of the second injection jets (68) are a same among one another.

13. The method according to claim 11, wherein the second injection jets (68) are injected into the combustion chamber (14) in a shape of a star in relation to one another.

14. The method according to claim 11, wherein the first injection jets (40) are injected with a first jet cone angle (β1) which ranges from 130 degrees inclusive to 160 degrees inclusive.

15. The method according to claim 14, wherein the second injection jets (68) are injected with a second jet cone angle (β2) which ranges from 100 degrees inclusive to 125 degrees inclusive.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0025] FIG. 1 shows, sectionally, a schematic side view of an internal combustion according to the invention for a motor vehicle; and

[0026] FIG. 2 shows, sectionally, a schematic top view of a combustion chamber of the internal combustion engine.

DETAILED DESCRIPTION OF THE DRAWINGS

[0027] In the figures, the same or functionally identical elements are provided with the same reference numerals.

[0028] In a schematic sectional view, FIG. 1 sectionally shows an internal combustion engine 10 formed as a stroke piston engine for a motor vehicle, such as a passenger vehicle or a commercial vehicle, for example. Here, the motor vehicle can be driven by means of the internal combustion engine 10. The internal combustion engine 10 has at least one cylinder 12, the combustion chamber 14 of which is delimited in the radial direction of the cylinder 12 by a cylinder wall 16. The radial direction of the cylinder 12 is illustrated in FIG. 1 by a double arrow 18. The cylinder wall 16 is formed, for example, by a cylinder housing, formed in particular as a cylinder crank housing, of the internal combustion engine 10. The combustion chamber 14 is delimited in the axial direction of the cylinder 12 by a piston 20 of the internal combustion engine 10 that can be received translationally moveably in the cylinder 12. In particular, the cylinder wall 16 forms a track 22, wherein the piston 20 can be supported on the track 22 in its radial direction and thus in the radial direction of the cylinder 12. The axial direction of the cylinder 12 coincides with the axial direction of the piston 20, wherein the radial direction of the cylinder 12 coincides with the radial direction of the piston 20.

[0029] The combustion chamber 14 is delimited in the axial direction of the cylinder 12 opposite the piston 12 by a combustion chamber roof 26 of the internal combustion engine 10. The combustion chamber roof 26 is formed, for example, by a cylinder head 28 of the internal combustion engine 10. The cylinder head 28 is, for example, a component formed separately from the cylinder housing and connected to the cylinder housing. Since the piston 20 is received translationally moveably in the cylinder 12, the piston 20 can be moved forwards and backwards between an upper dead center and a lower dead center in the axial direction of the cylinder 12 in relation to the cylinder wall 16, such that the piston 20 can be stroke adjusted.

[0030] The piston 20 has an annularly peripheral piston stage 32 which is arranged axially recessed in the piston 20 in comparison with an annularly peripheral piston crown 32 of the piston 20 and which merges into a piston hollow 36, arranged axially recessed in the piston 20 in relation to the piston stage 32, of the preferably integrally formed piston 20 via an annularly peripheral jet splitter contour 34 of the piston 20. The respective feature of the piston stage 32 being axially recessed in comparison with the piston crown 32 or that the piston hollow 36 is arranged to be axially recessed in relation to the piston crown 32 is to be understood to mean that the piston stage 32 is recessed in comparison with the piston crown 30 in the axial direction of the piston 20 and thus in the axial direction of the cylinder 12 or set back towards the piston hollow 36 or that the piston hollow 36 is set back in the axial direction of the piston 20 and thus in the axial direction of the cylinder 12 away from the combustion chamber roof 26 in comparison with the piston stage 32.

[0031] Furthermore, at least or exactly one injector 38 of the internal combustion engine 10 is allocated to the combustion chamber 14. The injector 38 is held on the cylinder head 28 and here arranged at least partially, in particular at least substantially or completely, in the cylinder head 28.

[0032] The piston 20 is coupled, for example flexibly, with an output shaft, formed as a crankshaft, of the internal combustion engine 10. The crankshaft can be rotated around an axis of rotation in relation to the cylinder housing. As a result of the flexible coupling of the piston 20 with the crankshaft, the translational movements of the piston 20 in the cylinder 12 are converted into a rotational movement of the crankshaft around its axis of rotation, whereby the crankshaft rotates around its axis of rotation in relation to the cylinder housing. Here, the internal combustion engine 10 is formed as a four-stroke engine, such that a respective work cycle of the internal combustion engine 10 comprises 720 degrees of crank angle, i.e., exactly two complete rotations of the crankshaft. Within the respective work cycle, at least one combustion process or several combustion processes proceed in the combustion chamber 14, as part of which a fuel-air mixture is combusted. In doing so, the piston 20 is driven, whereby the crankshaft is driven and thus rotated around its axis of rotation in relation to the cylinder housing. As is explained in more detail below, the fuel-air mixture comprises air which flows into or is introduced into the combustion chamber 14. Moreover, the fuel-air mixture comprises a fuel which is injected within the respective work cycle directly into the combustion chamber 14 by means of the injector 38. The fuel is preferably a liquid fuel. Furthermore, additionally returned exhaust gas can be present in the combustion chamber 14 if an exhaust gas return is provided. Preferably, the internal combustion engine 10 is formed as a self-igniting internal combustion engine, in particular as a diesel engine, such that the fuel is a diesel fuel. A method for operating the internal combustion engine 10 is described below, wherein the internal combustion engine 10 is operated in a fired operation during the method or by means of the method, during which the at least or preferably exactly one combustion process proceeds in the combustion chamber 14 within the respective work cycle. Thus, the method is a combustion method according to which the internal combustion engine 10 is operated in its fired operation. In particular, the internal combustion engine 10 is operated in a self-igniting operation during the method or by means of the method, as part of which the fuel-air mixture or a fuel-air-exhaust gas mixture is ignited in an independently sparking manner, i.e., without using an external ignition device, such as a spark plug, for example.

[0033] Within the respective work cycle for the respective combustion process, several first injection jets 40 are simultaneously injected by means of the injector 38 directly into the combustion chamber 14 in the shape of a star along their respective longitudinal central axes 41, which can be seen particularly well when seen together with FIG. 2. Here, in FIGS. 1 and 2, the first injection jets 40 are shown when impinging on the jet splitter contour 34. In the further course of the injection, in particular during the first expansion of the injection jets into the combustion chamber 14, the respective first injection jet 40 is divided by means of the jet splitter contour 34 into a first subset 42 entering into the piston hollow 36 (depicted as an arrow), into a second subset 44 entering into a region B between the piston crown 30 and the combustion chamber roof 26 via the piston stage 32 (depicted as an arrow) and into third subsets 46 (depicted as an arrow) (FIG. 2). The at least or exactly two third subsets 46 expand starting from the respective first injection jet 40 on both sides in the peripheral direction of the piston 20 in opposite directions along the piston stage 32 and collide between two adjacent injection jets 40 and are thus radially, i.e., in the radial direction of the piston 20, deflected inwardly in the direction of the injector 38. Here, the peripheral direction of the piston 20 is illustrated in FIG. 2 by a double arrow 48, wherein the peripheral direction runs around the axial direction, for example.

[0034] The respective injection jet 40 and thus the subsets 42, 44 and 46 are formed by respective parts or fuel parts of the fuel, which is injected within the respective work cycle by means of the injector 38 directly into the combustion chamber 14. Thus, the fuel is injected directly into the combustion chamber 14 within the respective work cycle by means of the injector 38 by forming the injection jets 40. The first subset 42 forms a first combustion front, and the second subset 44 forms a second combustion front. The respectively third subsets 46 deflected inwardly together form a third combustion front radially outwards into a gap 50 between the injection jets 40 or between two adjacent injection jets 40. A resulting current 58 (depicted as an arrow) formed from a swirl 52 (depicted as an arrow), a crushing gap current 54 (depicted as an arrow) and a jet current 56 (depicted as an arrow) deflect the injection jets 40 up-jet or upstream of the jet splitter contour 34 in the direction of the piston 20, such that the injection jets 40 furthermore impinge on the piston 20 with a piston 20 moving away from the cylinder head 28 in the expansion stroke substantially further into the region of the jet splitter contour 34.

[0035] In order to now be able to achieve a particularly effective combustion by optimally utilizing the combustion air present in the combustion chamber 14, first deflection means 62 and, alternatively to or in combination with the first deflection means, second deflection means 62′ are arranged in the piston stage 32, in particular in its stage chamber 60. Here, the first deflection means 62 divide the injection jets 40 striking the jet splitter contour 34 into third subsets 46 or, with the division into the third subsets 46, support them. The second deflection means 62′ can deflect the respective third subset 46 in the radial direction inwardly. It can be seen from FIG. 2 that the respective first deflection means 62 and the second deflection means 62′ are formed as a jet splitter or a nose. Moreover, it can be seen particularly well from FIG. 1 and FIG. 2 that the piston stage 32 has a stage wall 64, also referred to as a side wall, by means of which the piston stage 32 or the stage chamber 60 is delimited outwardly in the radial direction of the piston 20. Furthermore, the piston stage 32 has a stage floor 66, also referred to as the floor, by means of which the piston stage 32 or the stage chamber 60 is delimited in the axial direction of the piston 20 downwardly in opposition to the cylinder head 28. The respective nose here projects in the radial direction of the piston 20 outwardly from the stage wall 64 and in the axial direction of the piston 20 on the stage floor 66. Thus, the respective deflection means 62 and 62′ protrude from the stage wall 64 in the radial direction inwardly towards the stage chamber 60 and are connected to the stage floor 66. Furthermore, the first deflection means 62 are provided at an impingement point of the injection jets 62 on the jet splitter contour 34 in the piston stage 32 in the stage chamber 60, and the second deflection means 62′ are provided substantially starting from the injector 38 respectively centrally between two adjacent first injection jets 40 in the piston stage 32 in the stage chamber 60.

[0036] Moreover, the first injection jets 40 are injected directly into the combustion chamber 14 in the form of jet cones with a respective first jet breakup α.sub.1. To do so, the injector 38, for example, has first injection openings not described in more detail, via which the first injection jets 40 are injected directly into the combustion chamber 14. Thus, the first injection jets 40 are caused by means of the first injection openings, such that the first injection openings cause the respective first jet breakups α.sub.1.

[0037] Moreover, several second injection jets 68 provided in addition to the first injection jets 40 are simultaneously injected directly into the combustion chamber 14 with a respective second jet breakup α.sub.2 by means of the injector 38 for the combustion process or within the respective work cycle. Here, the respective first jet breakups α.sub.1 differ from the respective second jet breakups α.sub.2. The first injection jets 40 point along a respective first longitudinal central axis 41 in their injection direction of the respective first injection jets, are narrower or have a further expansion than the respective second injection jets 68 along a respective second longitudinal axis 69 in their injection direction of the respective second injection jets 68. In other words, the second injection jets 68, for example, are thus bushier or more bulbous with a thick jet lobe than the first injection jets 40 and have a greater jet breakup α.sub.2 with a further expansion transversely to its second longitudinal central axis 69 than the first injection jets 40 with a thin jet lobe, which has a smaller jet expansion transverse to its first longitudinal central axis 41. For this, the injector 38 has, for example, second injection openings not referred to in more detail provided in addition to the first injection openings, by means of which or via which the second injection jets 68 are injected directly into the combustion chamber 14. Thus, the second injection openings each cause a second injection jet 68 which respectively forms an injection jet 68 with a respective second jet cone angle α.sub.2. Here, the second injection jets 68 are flushed by the injector 38 in the direction of the piston 36 as a fourth subset based on an axial direction of the piston 20 in a jet cone angle β.sub.2 different from the first injection jets 40. The fourth subsets formed by the respective second injection jets 68 each form a fourth combustion front.

[0038] For example, a first part of the fuel, which is injected directly into the combustion chamber 14 within the respective work cycle by means of the injector 38, is injected through the first injection openings and thus directly into the combustion chamber 14 via the first injection openings. The first part of the fuel thus forms the first injection jets 40. Furthermore, for example, a second part of the fuel, which is injected directly into the combustion chamber 14 by means of the injector 38 within the respective work cycle, is injected through the second injection openings and thus injected directly into the combustion chamber 14 via the second injection openings. Here, the second part of the fuel forms the respective second injection jets 68. The first part and the second part form, for example, the fuel in total, which is injected directly into the combustion chamber 14 within the work cycle by means of the injector 38 in total. If further injections of first injection jets 40 and second injection jets 68 are injected into the combustion chamber 14 within a work cycle, all first and second parts form the sum of the fuel that is injected into the combustion chamber 14.

[0039] As can be seen particularly well from FIG. 2, the first injection jets 40 are injected into the combustion chamber 14 in the shape of a star when seen one below the other or in relation to one another. The second injection jets 68 are also injected into the combustion chamber 14 in the shape of a star when seen one below the other or in relation to one another. Moreover, it is provided that the first injection jets 40 and the second injection jets 68 are simultaneously injected into the combustion chamber 14 in the shape of a star in relation to one another.

[0040] Moreover, the first injection jets 40 are longer than the second injection jets 68. In particular, the first injection jets 40 reach further into the combustion chamber 14 than the second injection jets 68. Furthermore, the second injection jets 68 are wider than the first injection jets 40 and are thus bushier or more bulbous. The first jet breakups α.sub.1 are the same and the second jet breakups α.sub.2 are the same, such that the respective first jet breakup α.sub.1 differs from the respective second jet breakup α.sub.2.

[0041] It has been shown to be particularly advantageous when the first injection jets 40 with a first jet cone angle α.sub.1 are injected into the combustion chamber 14. The jet cone angle β.sub.1 includes the angle which the first injection jets 40 enclose. The respective first jet cone angle β.sub.1 ranges from 130 degrees inclusive to 160 degrees inclusive and can be, in particular, 150 degrees, while, for example, the respective second jet cone angle β.sub.1 ranges from 100 degrees inclusive to 125 degrees inclusive and can be, in particular, 120 degrees.

[0042] Moreover, it is provided that, when injecting the first injection jets 40 and the second injection jets 68, alternatingly follow on from one another in the peripheral direction of the piston 20 and thus the cylinder 12.

[0043] It can be seen particularly well in FIG. 1 that the respective first injection jet 40 is a narrow jet with high impulse, high K-factor and high he-rounding. The respective second injection jet 68 is a bushy jet with low impulse, low K-factor, i.e., low conicity and low he-rounding.

[0044] The respective injection jet 40 or 68 is formed by a respective fuel mass, also referred to as the injection mass, of the fuel. Here, the distribution of the injection masses between the injection jets 40 and 68 is conceivable in such a way that it corresponds to the mass of the combustion air available in this chamber, in particular in the chamber in which the respective injection jets 40 and 68 expand. Thus, a particularly advantageous combustion can be ensured.

LIST OF REFERENCE CHARACTERS

[0045] 10 Internal combustion engine [0046] 12 Cylinder [0047] 14 Combustion chamber [0048] 16 Cylinder wall [0049] 18 Double arrow [0050] 20 Piston [0051] 22 Track [0052] 24 Double arrow [0053] 26 Combustion chamber roof [0054] 28 Cylinder head [0055] 30 Piston crown [0056] 32 Piston stage [0057] 34 Jet splitter contour [0058] 36 Piston recess [0059] 38 Injector [0060] 40 Injector jet [0061] 41 Longitudinal central axis [0062] 42 First subset [0063] 44 Second subset [0064] 46 Third subset [0065] 48 Double arrow [0066] 50 Gap [0067] 52 Swirl [0068] 54 Crushing gap current [0069] 56 Jet current [0070] 58 Resulting current [0071] 60 Stage chamber [0072] 62, 62′ Deflection means [0073] 64 Stage wall [0074] 66 Stage floor [0075] 68 Second injection jet, fourth subset [0076] 69 Longitudinal central axis [0077] α.sub.1,2 Jet breakup [0078] β.sub.1,2 Jet cone angle [0079] B Region