Patent ID: 6505465
Filing Date: 2003-01-14
Classification: F01N,F02D

Abstract:
A device for controlling an internal combustion engine comprising:an air flow sensor provided in an intake pipe of the internal combustion engine to detect the amount of the intake air; temperature detector means and pressure detector means for detecting the temperature and the pressure of the air taken in by said internal combustion engine; air-fuel ratio detector means provided in the exhaust pipe of said internal combustion engine and for detecting the air-fuel ratio in the exhaust gas; EGR rate detector means for detecting the EGR rate of the exhaust gas recirculated into the intake air; a NOx purifying catalyst provided in the exhaust pipe of said internal combustion engine; NOx operation means for estimating the amount of NOx in the exhaust gas from a theoretical formula and an empirical formula based upon the amount of the intake air, temperature and pressure of the intake air, air-fuel ratio and EGR rate; and control means for controlling at least either said NOx purifying catalyst or a combustion state in said internal combustion engine in order to lower the amount of NOx emission wherein said NOx operation means estimates the oxygen concentration, nitrogen concentration and temperature of the combustion gas in said internal combustion engine from said theoretical formula and said empirical formula, and estimates the amount of NOx emission in the exhaust gas based upon said oxygen concentration, nitrogen concentration and temperature of the combustion gas.