METHOD FOR ESTIMATING SOX AMOUNT ACCUMULATED IN NOX TRAP

摘要

PROBLEM TO BE SOLVED: To provide a method and a device to make highly accurate decision on time when SOx accumulated in an NOx trap exceeds its maximum limit and operation is to be brought into a purification mode. SOLUTION: An engine control computer estimates an accumulating SOx amount stored in an NOx trap. When a storage volume exceeds a maximum value, operation s brought into an SOx purification mode. an SOx accumulation amount is estimated, based on a flow of fuel to an engine, an A/F, and a trap temperature. A purification mode is completed when a storage level of SOx is decreased to a value lower than a minimum threshold value level during purifying operation.