| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a failure diagnostic device for a fuel injection valve of internal combustion engine equipped at the exhaust system with a lean NOx catalyst and capable of lean combustion, whereby the change in the rate-of-flow characteristics resulting from a failure on the open side of the valve is sensed accurately, and at eventual failure, the aux. injection is controlled so as to prevent the catalyst from being overheated. SOLUTION: The presumptive value THCE of the catalyst outflow exhaust gas temp. is determined through annealing of the catalyst influx exhaust gas temp. THCI, and if the sensed value THCO of the catalyst outflow exhaust gas temp. is abnormally higher than the obtained value THCE (i.e., if the temp. difference between the upstream and downstream of the catalyst is over the specified value), judgement is passed that a failure exists in the injection system. At this time, the aux. injection amount QFINA for supplying a reducer to the catalyst is subjected to a decremental correction by a certain amount Q0 . By this correction, the catalyst is prevented from overheating, and also such an inconvenience is precluded that HC leaks to the downstream of the catalyst.</p> |
