| 摘要 |
PROBLEM TO BE SOLVED: To appropriately correct a target compression ratio to correspond to a delay in an EGR rate change during transition.SOLUTION: During transition, an EGR rate upstream of a throttle valve is estimated using a throttle-valve-upstream EGR rate map 61 from an EGR gas flow quantity Qegr at which EGR gas actually flows in an EGR valve 24, a total flow quantity Qtt at which the gas flows in an intake passage capacity between a merger point of an exhaust gas recirculation passage and the throttle valve, and a throttle valve flow quantity Qth at which the gas flows out via the throttle valve. An internal intake passage model 62 gives, to the EGR rate upstream of the throttle valve, a delay corresponding to a transport delay from the throttle vale to an intake port, thereby obtaining an internal-intake-port EGR rate estimated value. The target compression ratio is corrected in response to the difference between a target EGR rate at stationary time and the internal-intake-port EGR rate estimated value.SELECTED DRAWING: Figure 6 |
