DIAGNOSIS METHOD OF WASTE TIME DELAY DETERIORATION OF GAS SENSOR, AND DIAGNOSIS DEVICE OF WASTE TIME DELAY DETERIORATION OF GAS SENSOR

摘要

PROBLEM TO BE SOLVED: To provide a diagnosis method and a diagnosis device of waste time delay deterioration of a gas sensor capable of precisely diagnosing whether the gas sensor has deteriorated by waste time delay.;SOLUTION: When one period in which a target air/fuel ratio is changed between rich and lean sides is set to be a small unit diagnosis period, and the target air/fuel ratio is at a richer side than a target center air/fuel ratio and an actual air/fuel ratio calculated based on output from the gas sensor is at a leaner side than an area reference value during a middle unit diagnosis period corresponding to the five periods, the sum of areas F1-F5 obtained by integrating the deviation between the actual air/fuel ratio and the area reference value is compared with a rich-side deterioration criterion. Also, when the target air/fuel ratio is at a leaner side than the target center air/fuel ratio and the actual air/fuel ratio is at a leaner side than the area reference value, the sum of areas D1-D5 obtained by integrating the deviation between the actual air/fuel ratio and the area reference value is compared with a lean-side deterioration criterion. Based on both the comparison results, the presence or absence of the waste time delay deterioration is diagnosed.;COPYRIGHT: (C)2010,JPO&INPIT