EGR RATE DETERMINATION METHOD AND SYSTEM

摘要

The present invention relates to an EGR rate determining method, and a system capable of determining the EFR rate of too high and/or too low using a nitrogen oxide (NOx) sensor. To achieve this, an embodiment of the present invention for the EGR rate determining method comprises the steps of: checking each modeling value of nitrogen oxide (NOx), exhaust gas flow, and engine brake torque; detecting a temperature of cooling water and outside atmosphere; detecting an actual value of nitrogen oxide through a nitrogen oxide sensor, and calculating an expected nitrogen oxide value in accordance to a preset logic; dividing the actual nitrogen oxide value by the expected nitrogen oxide value; comparing a preset critical ratio value with a value obtained from dividing the actual nitrogen oxide value by the expected nitrogen oxide value; and determining whether the EGR is too high if the divided value is greater than the preset critical ratio, and if not as the EGR is too low.