| 摘要 |
PROBLEM TO BE SOLVED: To rapidly detect degrading with a high accuracy by maximally preventing emission from being lowered during diagnosis. SOLUTION: Impulse disturbances LR and RL are outputted by a predetermined times to a feedback control system. After the disturbances LR and RL are output, a differential value D<SB>O2</SB>obtained by differentiating an output PF from a linear air-fuel ratio sensor switch 4 is output. Based on the differential value D<SB>O2</SB>, the idle time L and a time constantτof the linear air-fuel ratio sensor are calculated as determination parameters. The output PF from the linear air-fuel ratio sensor switch 4 is determined to see whether it is converged or not and the generation of disturbance is reset at the time of expiration of the calculated idle time L. At the same time, when the output PF from the linear air-fuel ratio sensor switch 4 is determined to be converged after the disturbances RL and LR are reset, next disturbances RL and LR are generated. The absolute values ¾H<SB>dis</SB>¾ of the next disturbances RL and LR is increased only when a differential peak value D<SB>O2PK</SB>related to the previous disturbances RL and LR is lower than a predetermined threshold ThP. COPYRIGHT: (C)2007,JPO&INPIT
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