In a method for operating a spark-ignition, direct-injection internal combustion engine, wherein fuel is injected into a cylinder of the internal combustion engine and is ignited by a spark plug as a function of at least the load of the internal combustion engine, a crank angle is determined at whic
In a method for operating a spark-ignition, direct-injection internal combustion engine, wherein fuel is injected into a cylinder of the internal combustion engine and is ignited by a spark plug as a function of at least the load of the internal combustion engine, a crank angle is determined at which a first amount of fuel is injected into the cylinder during the intake stroke whereby a lean mixture is formed in the cylinder, subsequently, as a function of at least the load of the internal combustion engine, a crank angle is determined at which a second amount of fuel is injected, whereby a mixture cloud, which is richer than the lean mixture is formed in the lean mixture and a third amount of fuel is injected in the form of a stratified injection for forming a locally enriched and ignitable fuel/air mixture in the region of the spark plug close to an ignition time which is then ignited by the spark plug causing also combustion of the mixture cloud and the lean mixture.
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What is claimed is: 1. A method for operating a spark-ignition, direct-injection internal combustion engine having a cylinder (4) with a piston (17) and a cylinder head (19) with a fuel injector (3) and a spark plug (5), wherein fuel (2) is injected by means of an injector (3) into the cylinder (4)
What is claimed is: 1. A method for operating a spark-ignition, direct-injection internal combustion engine having a cylinder (4) with a piston (17) and a cylinder head (19) with a fuel injector (3) and a spark plug (5), wherein fuel (2) is injected by means of an injector (3) into the cylinder (4) of the internal combustion engine and is ignited by means of the spark plug (5), said method comprising the steps of: determining as a function of at least the load of the internal combustion engine, a crank angle (α1) at which a first injection (9) of fuel (2) takes place, and performing the first injection whereby a lean mixture (13), whose local air ratio (λ1) is greater than 1.0, is generated in the cylinder (4); subsequently, determining as a function of at least the load of the internal combustion engine, a crank angle (α2) at which a second injection (10) of fuel (2) takes place, and initiating a second injection whereby a mixture cloud (14) is formed, which is richer than the lean mixture (13) of the first injection and which is embedded in the lean mixture (13) and whose local air ratio (λ2) is less than or equal to 1.0, is generated in the cylinder (4); subsequently, initiating a third injection (11) of fuel (2) in the form of a stratified injection for generating a locally enriched and ignitable fuel/air mixture in the region of the spark plug (5) at least close in terms of time to an ignition time (12) and igniting the locally enriched fuel/air mixture. 2. The method as claimed in claim 1, wherein the three injections (9, 10, 11) are carried out in at least approximately the entire load range of the internal combustion engine. 3. The method as claimed in claim 1, wherein at low engine load, the first and the second injection (9, 10) takes place as a stratified injection in a compression stroke (7). 4. The method as claimed in claim 3, wherein the first injection (9) is carried out at a crank angle (α1) of approximately 60° before ignition top dead center (ITDC) and the second injection (10) at a crank angle (α2) of approximately 30° before ignition top dead center (ITDC). 5. The method as claimed in claim 1, wherein, at least at one of medium and high engine load, the first injection (9) is a homogeneous injection in an intake stroke (6), and the second injection (10) is a stratified injection in the compression stroke (7). 6. The method as claimed in claim 5, wherein, at medium engine load, the first injection (9) begins at a crank angle (α1) of approximately 300° before ignition top dead center (ITDC) and the second injection (10) begins at a crank angle (α2) of approximately 60° before ignition top dead center (ITDC). 7. The method as claimed in claim 5, wherein, at high load, the first injection (9) begins at a crank angle (α1) of approximately 300° before ignition top dead center (ITDC) and the second injection (10) begins at a crank angle (α2) of approximately 180° before ignition top dead center (ITDC). 8. The method as claimed in claim 1, wherein the air ratio (λ1) of the lean mixture (13) is selected such that a combustible but non-ignitable fuel/air mixture is generated. 9. The method as claimed in claim 1, wherein the air ratio (λ2) of the mixture cloud (14) formed by the second injection is selected such that a combustible and ignitable fuel/air mixture is generated. 10. The method as claimed in claim 1, wherein a global air ratio (λ) averaged over the cylinder volume and generated from all the injections (9, 10, 11) is in a range from approximately 1.0 inclusive to approximately 4.0 inclusive. 11. The method as claimed in claim 1, wherein the cylinder volume contains a proportion of inert gas at the beginning of the combustion. 12. The method as claimed in claim 1, wherein at least one of the injections (9, 10, 11) is carried out as a multiple injection, in particular as a double or triple injection. 13. The method as claimed in claim 1, wherein the third injection is coordinated in terms of time with the ignition time (12). 14. The method as claimed in claim 13, wherein the third injection has an injection end (15) in the region of the ignition time (12). 15. A method of operating a spark-ignition, direct-injection internal combustion engine which operates on the 4-stroke principle and has an exhaust-gas catalytic converter (1) during cold-running operation, in which fuel (2) 2s injected by means of an injector (3) into a cylinder (4) of the internal combustion engine and is ignited by means of a spark plug (5), which method comprises the following steps: performing in an intake stroke (6), a first injection of fuel (2) as an intake stroke injection (9), in which a lean, combustible but non-ignitable lean mixture (13) is generated in the cylinder (4); performing in a compression stroke (7) which follows the intake stroke (6), a second injection of fuel (2) as a compression stroke injection (10), in which a combustible and ignitable fuel/air mixture is generated in the cylinder; subsequently, performing a third injection of fuel (2) in the form of a stratified injection (11′) for generating a locally enriched and ignitable fuel/air mixture in the region of the spark plug (5) at least close in terms of time to an ignition time (12′), and igniting the locally enriched and ignitable fuel/air mixture of the third injection. 16. The method as claimed in claim 15, wherein the intake stroke injection (9) is carried out in such a way that an at least approximately homogeneous lean mixture (13) is generated in the cylinder (4). 17. The method as claimed in claim 16, wherein the homogeneous lean mixture (13) has an air ratio (λ1) of approximately 1.6. 18. The method as claimed in claim 15, wherein the compression stroke injection (10) is carried out in such a way that, within the homogeneous lean mixture (13), a mixture cloud (14) is formed which is richer than said homogeneous lean mixture (13). 19. The method as claimed in claim 18, wherein the richer mixture cloud (14) has an air ratio (λ2) of less than 1.0. 20. The method as claimed in claim 15, wherein the global air ratio (λ) averaged over the cylinder volume and generated from all the injections (9, 10, 11′) is in a range from approximately 1.0 inclusive to greater than 1.0, and is in particular between 1.0 inclusive and 1.05 inclusive. 21. The method as claimed in claim 15, wherein at least one of the intake stroke injection (9), the compression stroke injection (10) and the stratified injection (11′) is carried out as a multiple injection. 22. The method as claimed in claim 15, wherein the intake stroke injection (9) takes place at a crank angle (α) of approximately 260° before ignition top dead center (ITDC). 23. The method as claimed in claim 15, wherein the compression stroke injection (10) takes place at a crank angle (α) of approximately 30° before ignition top dead center (ITDC). 24. The method as claimed in claim 15, wherein the stratified injection (11′) is coordinated in terms of time with the ignition time (12′). 25. The method as claimed in claim 24, wherein the ignition time (12′) lies after ignition top dead center (ITDC) and in a crank angle range (α) of 0° to 35°, after ignition top dead center (ITDC). 26. The method as claimed in claim 24, wherein an injection end (15′) of the stratified injection (11′) coincides with the ignition time (12′). 27. The method as claimed in claim 15, wherein the injection quantities of at least one of the compression stroke injection (10) and the stratified injection (11′) are controlled by a control unit (16) as a function of an operating temperature of the exhaust-gas catalytic converter (1). 28. The method as claimed in claim 15, wherein the times of at least one of the compression stroke injection (10), the ignition (12′) and the stratified injection (11′) which is coupled to the ignition time (12′) are controlled by means of the control unit (16) as a function of the operating temperature of the exhaust-gas catalytic converter (1).
McGee, Brian G., Method and apparatus for delivering multiple fuel injections to the cylinder of an engine wherein the pilot fuel injection occurs during the intake stroke.
Duffy, Kevin P.; Fluga, Eric C.; Hafner, Gregory G.; McGee, Brian G.; Roth, Matthew R., Method and apparatus for delivering multiple fuel injections to the cylinder of an internal combustion engine.
Duffy,Kevin P.; Fluga,Eric C.; McGee,Brian G.; Roth,Matthew R.; Hafner,Gregory G., Method and apparatus for delivering multiple fuel injections to the cylinder of an internal combustion engine.
Kevin P. Duffy ; Eric C. Fluga ; Gregory G. Hafner ; Brian G. McGee ; Matthew R. Roth, Method and apparatus for delivering multiple fuel injections to the cylinder of an internal combustion engine.
Kevin P. Duffy ; Eric C. Fluga ; Gregory G. Hafner ; Brian G. McGee ; Matthew R. Roth, Method and apparatus for delivering multiple fuel injections to the cylinder of an internal combustion engine.
Pagot, Alexandre; Zaccardi, Jean-Marc, Fuel mixture combustion control method for a spark-ignition internal-combustion engine, notably a supercharged engine.
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