| 摘要 |
PURPOSE: An intake air control method for a lean NOx trap is provided to reach the target air-fuel ratio with a small variation by calculating the displacements of a throttle and an EGR valve and moving one of the throttle and the EGR valve which has a smaller displacement. CONSTITUTION: An intake air control method for a lean NOx trap comprises the steps of: determining whether to control an air-fuel ratio in order to remove NOx(S10), calculating an air reduction amount to satisfy the target air-fuel ratio from the current air-fuel ratio(S14), calculating the displacement a throttle and an EGR valve have to move in order to reduce air amount(S16), determining whether the calculated displacement of the throttle is greater than that of the EGR valve(S18), moving the EGR valve the calculated displacement(S20), determining whether the air-fuel ratio at the current driving point satisfies the target air-fuel ratio(S26), and moving the throttle the calculated displacement if the current air-fuel ratio does not satisfy the target air-fuel ratio(S28).
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