Patent ID: 7866306
Filing Date: 2011-01-11
Classification: F02D,F02M,Y02T

Abstract:
1. A control apparatus of an EGR control valve comprising: an EGR control valve in an exhaust gas recirculation passage for circulating exhaust gas of an combustion engine from an exhaust gas passage to an intake air passage; means for measuring a flow rate of EGR gas flowing in the exhaust gas recirculation passage; and means for controlling by receiving an input from said measuring means and closing said EGR control valve if the EGR-gas flow rate is smaller than a predetermined threshold value in a forward flow condition where the EGR gas is flowing from the exhaust side to the intake side of the internal combustion engine; wherein said controlling means calculates an approximate expression which expresses the variation of the EGR flow rate based on the EGR-gas flow rate at a plurality of time points, predicts a back flow start time at which the EGR-gas flow rate practically becomes zero based on the approximate expression, calculates the EGR-gas flow rate at a time point which is earlier than the back flow start time by a control time constant of the EGR control valve or more based on the approximate expression, and uses the calculated value as the predetermined threshold value.