AIR-FUEL RATIO SENSOR FAULT DIAGNOSIS SYSTEM Russian patent published in 2018 - IPC F02D45/00 

FIELD: engine devices and pumps.

SUBSTANCE: air-fuel ratio sensor fault diagnosis system comprising an exhaust gas purification catalyst disposed in the exhaust path of the internal combustion engine, an air-fuel ratio sensor on the inlet side located in the exhaust port from the inlet side of the exhaust gas purification catalyst in the exhaust gas flow direction, an air-fuel ratio sensor on the outlet side located in the exhaust port from the exhaust side of the exhaust gas purification catalyst in the exhaust gas flow direction, and a diagnostic device diagnosing the air-fuel ratio sensor at the outlet side for the fault, based on the outlet signals of these air-fuel ratio sensors. The diagnostic device estimates that air-fuel ratio sensor on the outlet side has a fault if output air-fuel ratio of air-fuel ratio sensor on the inlet side became a rich air-fuel ratio that is richer than the stoichiometric air-fuel ratio, and the output air-fuel ratio of air-fuel ratio sensor from the outlet side has changed from the air-fuel ratio, which is richer than the lean estimating reference air-fuel ratio of air-fuel ratio that is leaner than lean estimating reference air-fuel ratio. As a result, it is possible to accurately diagnose the fault of air-fuel ratio sensor from the outlet side when using the air-fuel ratio sensor as a sensor on the outlet side.

EFFECT: creation of a fault diagnosis system capable to accurately diagnose the fault in air-fuel ratio sensor from the outlet side.

12 cl, 13 dwg