| 摘要 |
A diagnostic device for a diesel engine comprises an airflow meter 12 at the intake to the engine. A control unit 10 predicts an intake pressure and an exhaust pressure of the engine from the fresh air flow-rate and engine rotation speed from sensor 13. Faults in exhaust gas recirculation (EGR) system 6, 7, 8, controlled by control unit 10 are diagnosed based on at least one of the predicted intake pressure and exhaust pressure. Preferably fault diagnosis is based on a differential pressure between the intake pressure and exhaust pressure, or on a comparison of an estimated EGR rate and target EGR rate found from the intake pressure and exhaust pressure. The system does not require the provision of any special sensors. Smoke emission is also reduced by limiting the maximum fuel injection amount of the engine. |
