| 摘要 |
PROBLEM TO BE SOLVED: To provide a diagnosis device capable of performing failure diagnosis of an EGR system, even when a detector for a state quantity related to an operation state is faulty. SOLUTION: A failure diagnosis device for an EGR system includes an air supply flow rate calculation part 65 for determining an air supply flow rate when the EGR system is normal based on engine rotation speed and air supply pressure, an air supply flow rate detector 66 for detecting an actual air supply flow rate, a temperature difference calculation part 62 for determining a temperature difference between a temperature of EGR gas merged with supply air and an air supply temperature when the EGR system is normal based on the engine rotation speed and a fuel injection amount, and a temperature difference detector 61 for detecting a temperature difference between an actual EGR gas temperature and the air supply temperature, and when at least one of the difference between the air supply flow rate determined by the air supply flow rate calculation part and the air supply flow rate detected by the air supply flow rate detection part and the difference between the temperature difference determined by the temperature difference calculation part and the temperature difference detected by the temperature difference detector is larger than a set value, determines that the EGR system is faulty. COPYRIGHT: (C)2012,JPO&INPIT |
