| 摘要 |
PROBLEM TO BE SOLVED: To provide an abnormality diagnosis device for air-fuel ratio sensor suitable for an air-fuel ratio sensor provided in a compression ignition type internal combustion engine. SOLUTION: The abnormality diagnostic device includes a means for calculating a computational air-fuel ratio A/Fk based on a fuel injection amount and an intake air amount, and a means for determining the abnormality of the air-fuel ratio sensor, based on the computational air-fuel ratio, and an actual air-fuel ratio A/Fr detected by the air-fuel ratio sensor, the computational air-fuel ratio being changed comparatively rapidly as an operating state of the internal combustion engine changes comparatively rapidly according to engine operation requirements. The air-fuel ratios are not forcibly changed and fluctuated, so that the deterioration of exhaust emission and combustion state during abnormality diagnosis, and deteriorations in vibrations, noise, etc. can be reliably prevented. COPYRIGHT: (C)2009,JPO&INPIT
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