EXHAUST CLEANING SYSTEM FOR INTERNAL COMBUSTION ENGINE

摘要

PURPOSE:To improve control precision and cleaning performance by detecting the emission state after exhaust cleaning with two oxygen sensors, and correcting the air-fuel ratio feedback control based on one oxygen sensor on the upstream side. CONSTITUTION:An oxygen sensor S1 is located on the exhaust passage B of an engine A and detects the oxygen concentration of engine exhaust. An air-fuel ratio feedback control means C sets the feedback correction quantity based on the detected oxygen concentration and feedback controls the air-fuel ratio of a mixture. A three-way catalyst D cleans the component in the engine exhaust. Two separate oxygen sensors S2 and S3 are arranged in series on the downstream side of the three-way catalyst D. Outputs from both oxygen sensors S2 and S3 on the downstream side are monitored, and the deterioration and abnormality of an oxygen sensor S1 on the upstream side are judged. The proportional portion of the feedback control constant is corrected by a correcting means E according to the judged result.