Patent ID: 6871492

Claim:
A process for controlling the mixture composition for an Otto engine with an NOx storage catalyst during a regeneration phase, the process comprising: controlling, to the value of one, a λ-value (λM) of an exhaust gas fed to the NOx storage catalyst during a regeneration phase as a function of a λ-value (λK) of an exhaust gas emitted by the NOx storage catalyst, wherein the step of controlling the λ-value (λM) of the exhaust gas fed to the NOx storage catalyst includes controlling the λ-value (λM) such that the λ-value (λK) of the exhaust gas emitted by the NOx storage catalyst does not fall under a value of one or falls only insignificantly under a value of one; initiating the regeneration phase when an NOx content of the exhaust gas emitted by the NOx storage catalyst exceeds a predetermined value; terminating the regeneration phase when the λ-value (λK) of the exhaust gas emitted by the NOx storage catalyst falls below a predetermined value; controlling the λ-value (λM) of the exhaust gas fed to the NOx storage catalyst at the beginning of the regeneration phase to a constant pilot value (λREG), and starting the control of the λ-value (λK) to the value of one only after the λ-value (λK) of the exhaust gas emitted by the NOx storage catalyst falls below a predetermined intervention value (λi), wherein the step of controlling the λ-value (λM) of the exhaust gas to a constant pilot value (λREG) includes making a predetermined afterinjection and controlling the λ-value of the main combustion such that the λ-value (λM) value of the exhaust gas fed to the NOx storage catalyst assumes the constant pilot value (λREG); and controlling the λ-value (λM) of the exhaust gas fed to the NOx storage catalyst according to the formula λ M =λ REG +k *(λ i −λ K ) wherein k is a constant.