Patent ID: 8738273

Claim:
An EGR system control method of an engine, the method comprising: calculating a target mass flux ({dot over (m)} egr d ) of EGR gas flowing through an EGR line; calculating a target effective flow area (EFA) of an EGR valve disposed in the EGR line; calculating an EGR flow sensitivity by dividing the target mass flux with the effective flow area; and controlling a real opening rate of the EGR valve by applying the EGR flow sensitivity to a target opening rate of the EGR valve; wherein the target effective flowing area (EFA) is calculated by: EFA d = m . egr d ⁢ R exh ⁢ T exh P exh · 1 PR 1 k ⁢ { 2 ⁢ ⁢ k k - 1 ⁢ ( 1 - PR k - 1 k ) } , ⁢ ( if ⁢ ⁢ PR > P CR ) wherein R exh is a gas constant of exhaust gas, T exh is a temperature of exhaust gas, PR is a front/rear pressure ratio of the EGR valve, k is a specific heat ratio, and P CR is a critical pressure ratio of the orifice flow.