| 摘要 |
PROBLEM TO BE SOLVED: To relate to a variable valve gear for an internal combustion engine, and to effectively suppress degradation of NOx emission.SOLUTION: A control device of an internal combustion engine has variable valve gears 13, 14 that can arbitrarily set opening timing and closing timing of intake and exhaust valves. The control device includes: a target in-cylinder oxygen concentration computing section 61 which computes a target oxygen concentration in a cylinder to suppress an NOx emission amount in a next cycle to a predetermined value or lower; a combustion state computing section 63 which computes an in-cylinder oxygen concentration based on the combustion state of the last cycle; a target internal EGR amount computing section 65 which computes a target residual gas amount to decrease the oxygen concentration in the cylinder in the next cycle down to the target oxygen concentration, when the computed in-cylinder oxygen concentration is higher than the computed target oxygen concentration; an overlap period computing section 66 which computes valve opening timing and closing timing to control the in-cylinder residual gas amount in the next cycle to the target residual gas amount; and an intake and exhaust valve operation control section 68 which controls opening and closing actions of the intake and exhaust valves 11, 12 at the computed valve opening timing and closing timing. |
