Estimating the oxygen concentration in the intake manifold of internal combustion engines

摘要

The invention provides a method for estimating the oxygen concentration in the intake manifold of an multi-cylinder i.c. engine having an intake manifold, an exhaust manifold, an EGR system, a throttle valve and an air mass sensor for measuring a fresh air flow mDotthrentering the intake manifold through the throttle valve. The method comprises the steps of (a) estimating the total gas flow mDotoentering the cylinders; (b) calculating the EGR gas flow mDotegr; (c) calculating the air fraction f_air_emof the gas flowing in the exhaust manifold; (d) calculating the air mass mim_airentering the cylinders based on the air fraction f_air_emof the gas flowing in the exhaust manifold, the total gas flow mDotoentering the cylinders, the EGR gas flow mDotegrand on the fresh air flow mDotthr; (e) calculating the total mass mimin the intake manifold based on the fresh air flow mDotthr, the EGR gas flow mDotegrand on the total gas flow mDotoentering the cylinders; (f) calculating the air fraction fair_imin the intake manifold based on the air mass mim_airentering the cylinders and on the total mass mimin the intake manifold, and (g) calculating the oxygen mass concentration [O2]mimin the intake manifold based on the air fraction fair_imin the intake manifold.