METHOD AND APPARATUS FOR PURIFYING EXHAUST GAS

摘要

PURPOSE:To enhance the NOx and CO purifying ratios of an exhaust gas purifying catalyst. CONSTITUTION:An air supply passage 5 supplying air to the part on the just upstream side of a catalyst 4 is connected to an exhaust passage 3 supplying HC and NOx to the catalyst 4 and an opening and closing valve 6 is provided to the air supply passage 5 and, when the catalyst 4 becomes high temp., the opening and closing valve 6 is driven to intermittently supply air to the catalyst 4 on the upstream side thereof.