| 摘要 |
<p>PURPOSE:To reduce the increase in the fluctuation of driving torque by prohibiting operation at a rich fuel-air ratio for regenerating an NOx absorbent during the power-on down shift operation of an automatic transmission. CONSTITUTION:An NOx absorbent 18 is laid in an engine exhaust passage 17 and an engine is normally operated at a lean air-fuel ratio, thereby causing the absorbent 18 to absorb NOx contained in exhaust gas. Also, an engine air- fuel ratio is selected at the rich side, when an NOx absorption amount increases, thereby regenerating the absorbent 18. In addition, an electronic control circuit 30 for controlling the engine is provided to prohibit the re-start of operation at a rich air-fuel ratio for regenerating the absorbent 18 over the preset time from the synchronization of the the rotation of transmission input and output shafts during the power-on down shift operation of an automatic transmission. Also, constitution is so made that the operation, if already under way at a rich air-fuel ratio, is stopped.</p> |
