CONTROL UNIT FOR EXHAUST GAS PURIFYING APPARATUS

摘要

PM elimination or sulfur release are performed on both exhaust systems (exhaust passages 13L, 13R) using a common procedure regardless of the state of a catalyst arranged in each one of the exhaust systems. This reduces the number of recovery cycles of the catalysts and suppresses increase of fuel consumption caused by the PM elimination and the sulfur release compared to a case in which the PM elimination/sulfur release is carried out each time a request for catalyst control is generated by one of the exhaust systems. In the PM elimination control, the PM elimination is performed using a catalyst exhibiting a lowest catalyst bed temperature of the catalysts as a reference. In this manner, PM is prevented from remaining unburned. Further, in the sulfur release control, the sulfur release is performed using an average of catalyst bed temperatures of the catalysts as a reference. This maximally suppresses thermal deterioration of the catalysts and ensures sufficient release of sulfur.