| 摘要 |
An exhaust gas recirculation control system for an internal combustion engine comprises sensors detecting operating conditions of the engine, an air-flow meter detecting an actual intake-air flow rate, an exhaust-gas-recirculation passage connecting an exhaust manifold with an intake manifold, an exhaust-gas-recirculation control valve device disposed in the exhaust-gas-recirculation passage for regulating an EGR rate. An electronic control unit is electronically connected to the sensors and the exhaust-gas-recirculation control valve device. The control unit arithmetically calculates a basic EGR rate as a function of a first predetermined engine operating condition containing engine speed and load, and calculates a first correction factor as a function of a second predetermined engine operating condition, such as engine coolant temperature, and estimates an intake-air flow rate from the first predetermined engine operating condition, the basic EGR rate, and the first correction factor, and calculates a second correction factor from a ratio of the actual intake-air flow rate to the intake-air flow rate estimated for feedback-correction to the basic EGR rate. The control unit interrelatively makes a first EGR-rate correction based on the first correction factor and a second EGR-rate correction based on the second correction factor with respect to the basic EGR rate to produce the final desired EGR rate, and then executes EGR control on the basis of the final desired EGR rate. <IMAGE> |
