| 摘要 |
PROBLEM TO BE SOLVED: To provide a technique of protecting an intake system engine member such as compressor from excessive temperature rise and suitably inhibiting generation amounts of NOx and smoke in a situation that temperature of exhaust gas becomes high. SOLUTION: An EGR system comprises a low-pressure EGR passage connecting an exhaust passage downstream of a turbine and an intake passage upstream of the compressor. When the temperature of exhaust gas recirculated to an internal combustion engine through the low-pressure EGR passage exceeds a predetermined reference temperature, a quantity of low-pressure EGR gas is corrected for reduction by decreasing an opening of a low-pressure EGR valve (S305, S306) and an effective compression ratio of cylinders of the internal combustion engine is lowered by advancing or retarding a valve close timing of an intake valve in an intake stroke based on a reduction correction quantity of the low-pressure EGR gas (S307). A quantity of the low-pressure EGR gas flowing into an intake system is reduced and therefore excessive temperature rise of the intake system is inhibited. Cylinder temperature is lowered and therefore increase of the NOx generation amount due to insufficiency of EGR can be avoided. COPYRIGHT: (C)2008,JPO&INPIT
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