| 摘要 |
PCT No. PCT/JP95/00275 Sec. 371 Date Oct. 6, 1995 Sec. 102(e) Date Oct. 6, 1995 PCT Filed Feb. 24, 1995 PCT Pub. No. WO95/23284 PCT Pub. Date Aug. 31, 1995Provided is an apparatus for detecting a volatility of fuel supplied to an engine, in order to ensure a more precise acceleration dependent fuel increasing-correction during air-fuel-ratio feed-back control. When the air-fuel-ratio feed-back control begins after engine starting (S4), a determination is made as to whether the engine is in a low exhaust-temperature state on the basis of an engine coolant temperature Tw (S5). When the exhaust temperature is low, an average value alpha av of an air-fuel-ratio feed-back correction factor alpha is derived (S6, S7), and then the average value alpha av is compared with a reference value (S8). In case that the fuel supplied to the engine is a heavy-gravity fuel of a low volatility, since there are great amounts of hydrocarbons HC in exhaust gases and with a great consumption of oxygen a control point of the air-fuel-ratio feed-back control, which point can be indicated by the average value alpha av, shifts to a leaner side. On the basis of the shift of the control point to the leaner side, during the air-fuel-ratio feed-back control, a discrimination is made as to whether the fuel supplied to the engine is a heavy-gravity fuel of a low volatility or a light-gravity fuel of a high volatility (S9, S10). |
