| 摘要 |
<p>PURPOSE: To know the conversion performance of the catalyst precisely by modulating a fuel control signal in a predetermined successive condition, determining a mean value of the signal and the oxygen-storage capability of the catalyst by means of the signal of the exhaust gas sensor rearward of the catalyst and indicating a fault when it is determined that the oxygen-storage capability is insufficient. CONSTITUTION: A fuel flow control device 1 is arranged in an intake line 2 of an internal combustion engine 3. Exhaust gas sensors 4, 5 are arranged forward and rearward of a catalyst 6 in an exhaust gas pipe 7. The fuel flow control device 1 provided with a closed loop control 11 and a control value generator 13 is driven and the remanent oxygen volume in the combusted exhaust gas is detected by the sensors 4, 5. Remaining oxygen volume in exhaust gas changed due to oxygen-storage capability of the catalyst is detected by the exhaust gas sensor 5. The control provided with a combination of a means 14 for regulating a control factor FR and a sequence control means 16 and the like is controlled. If it is determined that the oxygen-storage capability is insufficient, a fault signal is outputted to a means 23. In this way, the conversion performance loss of the catalyst is known precisely.</p> |
