Apparatus and method for monitoring NOx storage catalytic converters
AssigneeVolkswagen Aktiengesellschaft
InventorsAxel Lang, Jens Druckhammer, Frank Schulze
Life of this patent
Estimating the term…
Abstract
A method and apparatus is provided for monitoring the operation of a NOx storage catalytic converter in the exhaust stream of an internal combustion engine. The NOx content of the gas stream upstream and downstream of the catalytic converter is measured and used to determine storage efficiency. This is compared to a threshold value, and if the threshold value is not met a regeneration process is performed. The storage value is measured after regeneration to determine if the catalytic converter is faulty.
Claims19
A method for monitoring operation of an NOx storage catalytic converter in the exhaust stream of a lean running internal combustion engine, comprising
- a. determining NOx exhaust gas concentrations upstream and downstream of said catalytic converter;
- b. determining an NOx storage efficiency ETANOX from said NOx exhaust gas concentrations;
- c. comparing said NOx storage efficiency etanox with a threshold value NOxMAX and determining if said threshold value is not met;
- d. if said threshold value is not met performing at least one regeneration step selected form NOx regenerating and desulfating;
- e. repeating the determination of storage efficiency according to steps a and b to derive a new value of storage efficiency;
- f. comparing said new value to said threshold value NOxMAX;
- and
- g. if said new value does not meet said threshold value, signalizing a catalytic converter fault.
Dependencies are inferred from the claim text.