| 摘要 |
PROBLEM TO BE SOLVED: To prevent a catalyst of an exhaust emission control device from being overheated. SOLUTION: When accelerator-on/accelerator-off is frequently repeated, a catalyst overheating counter C is increased or decreased by an addition value reflecting an unburnt gas amount flowing into a purifying device by fuel cut return increase and a subtraction value reflecting an unburnt gas amount a three-way catalyst purifies by air (oxygen) flowing into the purifying device by fuel cut, and thereby, a degree of the unburnt gas amount contributing to temperature rise of the three-way catalyst can be estimated. After the catalyst overheating counter C is equal to or more than a first threshold Cref1 showing the overheating state of the three-way catalyst and until the catalyst overheating counter C is less than a second threshold Cref2, a value 1 is set on a return increase forbidding flag F so as to forbid fuel cut return increase, and fuel cut return increase is prevented, thereby preventing the three-way catalyst of the purifying device from being overheated. COPYRIGHT: (C)2009,JPO&INPIT |
