CONTROLLER DEVICE FOR NOX CATALYZER

摘要

PROBLEM TO BE SOLVED: To improve the accuracy of an estimating means by adding a state of air-fuel mixture in a cylinder and a quantity of internal exhaust gas recirculation and actually using the value of a running meter for estimating a degree of deterioration due to an adsorbing quantity of NOx and SOx. SOLUTION: When driving is carried out in homogeneous air-fuel mixture as well as when it is carried out in stratified super lean, a NOx discharge quantity is estimable by an air-fuel ratio, but in the intermediate air-fuel ratio, there are possible for both of homogeneous and stratified driving, so that the NOx discharge quantity is uniquely determinable by the air-fuel ratio. Accordingly, stratified driving or homogeneous driving is took into consideration for the estimation 102 of NOx adsorbing quantity (block 101). Concretely, this judgment is carried out by a span of injection timing. Subsequently, in the cae where the estimate value has exceeded the specified value (block 103), it is shifted to the rich control (block 104). The NOx estimate value is stored in a non-volatile memory (block 105). This memory uses such one making the numerical value storable even if in time of key-off and a battery is removed. In this connection, the estimated value is utilized for the life diagnosis of a catalyzer.