Daimler Ag

Daimler Chrysler Ag

Bernd Köhler

Michael Oechsle

Christoph Lux

Matthias Werner

Andreas Spieth

Oliver Platzek

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.

Method of operating a spark ignition internal combustion engine

In a method for operating a spark-ignition internal combustion engine with direct fuel injection in the post-start phase at low temperatures, fuel is supplied to the combustion air in a pilot injection (M) of a first fuel quantity during an intake stroke of the internal combustion engine such that the pilot injection (M) forms a homogeneous, lean air/fuel mixture (&#x3bb;&#x3e;1) in substantially the entire combustion chamber, and a main injection (M) of a second fuel quantity is subsequently injected into the combustion chamber during a compression stroke directly before the ignition time (ZT), said main injection (M) forming in the region of the spark plug a stratified, rich air/fuel mixture (&#x3bb;&#x3c;1), which is then ignited by the spark plug.

Method for operating an internal combustion engine with direct fuel injection during a post-start phase

In a method of operating an internal combustion engine with direct fuel injection such that, in the engine startup period, a three-way catalytic converter disposed in the engine exhaust system is rapidly heated to a working temperature, in that a fuel quantity which is injected is injected in two separate injection steps with the first fuel volume being injected during the intake stroke and the second fuel volume being injected during the expansion stroke so as to form immediately before the ignition instant a rich stratified charge cloud in the region of the spark plug thereby ensuring reliable ignition of the stratified cloud while, overall, achieving a lean fuel/air mix in the combustion chamber.

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Donzdorf, Germany

Bernd Köhler