| 摘要 |
<p>PURPOSE:To provide a fault diagnostic device of an internal combustion engine capable of accurately performing the deterioration diagnosis of the internal combustion engine regardless of the magnitude of the engine revolving speed and capable of accurately performing the deterioration diagnosis of the fluctuation factor detecting means of the internal combustion engine. CONSTITUTION:Output signals S3, S4 of front and rear O2 sensors 3, 4 are fed to sampling sections 14A, 14B via high-pass filters 12A, 12B and low-pass filters 13A, 13B, and they are fed to a judgment section 17 from a correlation coefficient calculation section 18, a sequence deterioration index calculation section 16A, a final deterioration index calculation section 16B, and a comparison section 16C. Fixed angle signals from an engine rotation angle sensor 25 are fed to the sampling sections 14A, 14B, and data are sampled at each fixed angle. The output signal S3 of the front O2 sensor 3 is fed to a sampling section 21 from a low-pass filter 19, fixed time signals of a fixed time signal generation section 20 are fed to the sampling section 21, and data are sampled at each fixed time. The output signal of the sampling section 21 is fed to a judgment section 24 from a differential filter 22 and a comparison section 23.</p> |
