Patent ID: 6199374
Filing Date: 2001-03-13
Classification: B01D,F01N,F02B,F02D,F02M,Y02T

Abstract:
An exhaust gas purifying device for an engine having an exhaust passage through which exhaust gas including excess oxygen flows, comprising:a catalyst arranged in the exhaust passage to purify the exhaust gas, the catalyst having an oxidizing ability;a feeding device that feeds a reducing agent to the catalyst to make the air-fuel ratio of the exhaust gas flowing into the catalyst rich when sulfate adsorbed in the catalyst is to be desorbed and reduced;a judging device that obtains an amount of sulfate adsorbed in the catalyst and judges whether the adsorbed sulfate amount is larger than a predetermined amount; anda controller that controls the feeding device to feed the reducing agent to the catalyst temporarily to desorb the adsorbed sulfate from the catalyst and to reduce the sulfate when the adsorbed sulfate amount is judged to be larger than the predetermined amount;wherein a rich time, which is a time during which the air-fuel ratio of the exhaust gas flowing into the catalyst is made rich when the sulfate absorbed in the catalyst is to be desorbed and reduced, is controlled in accordance with an engine operating condition.