Patent ID: 8037737

Claim:
A method of estimating an exhaust gas temperature T 3 in an internal combustion engine of a vehicle at an outlet of an EGR circuit with which the engine is equipped, the vehicle including an electronic temperature estimating computer, the method comprising: measuring an EGR circuit inlet temperature T 0 ; calculating, using the electronic temperature estimating computer, a temperature T W of a wall of an EGR duct conveying exhaust gas in the EGR circuit; calculating, using the electronic temperature estimating computer, a temperature T 2 of the exhaust gas at an inlet of an EGR cooler of the EGR circuit; estimating, using the electronic temperature estimating computer, the exhaust gas temperature T 3 at the outlet of the EGR circuit based on the EGR circuit inlet temperature T 0 , the temperature T 2 of the exhaust gas at the inlet of the EGR cooler, and a thermal energy loss of the exhaust gas in the EGR cooler of the EGR circuit, wherein the temperature T W of the wall is calculated according to the following: { T w ⁢ ⁢ ∞ = T 0 ⁡ ( 1 - ɛ 1 ) + ɛ 1 ⁢ T water ⅆ T w ⅆ t = 1 τ w ⁡ [ T w ⁢ ⁢ ∞ - T w ] where: ɛ 1 = K 1 K 1 + Cp egr ⁢ Q egr ⁢ ɛ 2 ; K 1 =constant; τ w =Time constant of the EGR duct upstream of the EGR cooler; T w∞ =Instantaneous wall temperature (with zero wall thermal inertia); ε 1 =external efficiency of the EGR duct upstream of the EGR cooler upon simplifying predetermined differential equations; and ε 2 =Internal efficiency of the EGR duct upstream of the EGR cooler upon simplifying the predetermined differential equations.