Patent ID: 8020369

Claim:
A method for mixture control for an internal combustion engine including at least one catalytic converter disposed in an exhaust system of the internal combustion engine, an oxygen sensor located downstream of the catalytic converter and a λ-closed-loop control, comprising: ascertaining a value for loading of the catalytic converter with oxygen; and changing the mixture as a function of the ascertained value, the changing including at least one of: (a) changing the mixture in a direction of rich exhaust gas when the ascertained value of the oxygen loading has increased by more than a first predefined measure within a predetermined time span; (b) changing the mixture in a direction of lean exhaust gas when the ascertained value of the oxygen loading has dropped by more than a second predefined measure within a predetermined time span; (c) changing the mixture in a direction of rich exhaust gas, by a predetermined value delta-λF, if the value of the oxygen loading lies above a first limiting value B 1 and a signal of the oxygen sensor deviates from a predetermined setpoint value SMD in a direction of lean exhaust gas, by at least a predetermined amount delta-M 1 , and the signal of the oxygen sensor has exceeded a predetermined setpoint value SSA in the direction of rich exhaust gas, by an amount of at least deltaF 1 , since a last overrun fuel cutoff phase of the internal combustion engine; and (d) changing the mixture in the direction of lean exhaust gas, by a predetermined value delta-λM, if the value of the oxygen loading lies below a second limiting value B 2 and the signal of the oxygen sensor deviates from a predetermined setpoint value SFD in the direction of rich exhaust gas, by at least a predetermined amount deltaF 2 , and the signal of the oxygen sensor has dropped below a predetermined setpoint value SFB in the direction of lean exhaust gas, by an amount of at least deltaF 2 , since a last rich-burn operating phase of the engine.