EXHAUST PURIFICATION SYSTEM OF INTERNAL COMBUSTION ENGINE

摘要

An exhaust purification system comprises an exhaust purification catalyst, a downstream side air-fuel ratio sensor and a control device. The control device makes the air-fuel ratio of the exhaust gas change to an air-fuel ratio at a rich side from the prior air-fuel ratio as air-fuel ratio rich increasing control when the air-fuel ratio of the exhaust gas is made a rich air-fuel ratio and the output air-fuel ratio of the downstream side air-fuel ratio sensor is maintained at a lean judged air-fuel ratio or more, and judges that the downstream side air-fuel ratio sensor suffers from an abnormality, when, due to the air-fuel ratio rich increasing control, the air-fuel ratio of the exhaust gas is made to change to the rich side air-fuel ratio and the output air-fuel ratio of the downstream side air-fuel ratio sensor changes to the lean side.

主权项

1. An exhaust purification system of an internal combustion engine, comprising an exhaust purification catalyst provided at an exhaust passage of the internal combustion engine, a downstream side air-fuel ratio sensor provided in the exhaust passage at a downstream side in the direction of flow of exhaust from the exhaust purification catalyst, and a control device controlling the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst and diagnosing abnormality of the downstream side air-fuel ratio sensor, wherein
the control device is to make the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst change to an air-fuel ratio at a rich side from the prior air-fuel ratio as air-fuel ratio rich increasing control when the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst is made a rich air-fuel ratio richer than the stoichiometric air-fuel ratio and the output air-fuel ratio of the downstream side air-fuel ratio sensor is maintained at a lean judged air-fuel ratio leaner than the stoichiometric air-fuel ratio or more, and is to judge that the downstream side air-fuel ratio sensor suffers from an abnormality, when, due to the air-fuel ratio rich increasing control, the air-fuel ratio of the exhaust gas flowing into the exhaust purification catalyst is made to change to the rich side air-fuel ratio and the output air-fuel ratio of the downstream side air-fuel ratio sensor changes to the lean side.