| 摘要 |
PROBLEM TO BE SOLVED: To provide a technique that an exhaust recirculation device of an internal combustion engine controls an EGR gas having an accurate EGR gas ratio, even when the accuracy of evaluating a front-and-back differential pressure between an inlet and an outlet of a low pressure EGR device is reduced. SOLUTION: When the front-and-back differential pressure between the inlet and the outlet of the low pressure EGR device is lower than a predetermined differential pressure which is a threshold whether the accuracy of evaluating the differential pressure is reduced: an amount of HC in an exhaust is estimated from an engine speed, a fuel injection amount of the internal combustion engine, and an exhaust flow rate; a heating value of an oxidation catalyst is estimated from an exhaust temperature on the upstream of the oxidation catalyst and the amount of HC; a purifying rate of the oxidation catalyst is estimated from the heating value; SV ratio is estimated from the exhaust temperature on the upstream and the purifying rate of the oxidation catalyst; a gas flow rate of passing through the oxidation catalyst is calculated from the SV ratio; and an amount of recirculation of the low pressure EGR gas and a high pressure EGR gas are controlled according to a relationship between the gas flow rate of passing through the oxidation catalyst and a target flow rate. COPYRIGHT: (C)2011,JPO&INPIT
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