Method and apparatus for desulphating a NOx trap

摘要

An engine control apparatus comprises :
a NOx trap located in the exhaust passage of a multi-cylinder engine ;a catalytic converter located in said exhaust passage upstream of said NOx trap, the catalytic converter having a lower oxygen storage capacity than said NOx trap; anda computer programmed to:
estimate when the trap should be purged of accumulated SOx,adjust the A/F of the mixture supplied to the engine to raise the temperature of the trap (32) to a purge temperature, andbias toward a rich A/F when the trap reaches said purge temperature to purge the trap of SOx.