Patent ID: 7152573

Claim:
A method for operating an internal combustion engine with exhaust gas purification system, in which a rich-burn mode of the internal combustion engine with a rich exhaust gas composition or a lean-burn mode of the internal combustion engine with a lean exhaust gas composition is set alternately, and in which a quantity of fuel which is introduced during a combustion cycle of the internal combustion engine is introduced by means of at least one preinjection, at least one main injection and at least one afterinjection, comprising: preinjecting fuel at an early time in the rich-burn mode in order to achieve a prehomogenized mix in the combustion chamber, the quantity of fuel injected during preinjection being set, and a combustion chamber pressure being lowered by intake air throttling, so that a mix which is not initially ignitable is present in the combustion chamber, adding the main injection to the prehomogenized mix in the combustion chamber in order to improve ignitability of the mix which is present in the combustion chamber, carrying out combustion of the at least one preinjection and of the at least one main injection under an excess of oxygen, and setting a rich exhaust gas composition by way of the at least one afterinjection.