Method of estimating engine charge

摘要

Method of estimating the total charge to cylinders (123) of an internal combustion (105) engine where the total charge comprises the sum of the air charge and the EGR charge. The total charge is estimated by determining a linear total charge versus MAP reference function at selected engine speeds and at a preselected reference (stored) barometric pressure, reference (stored) engine coolant temperature, and reference (stored) manifold air charge temperature and determining a current barometric pressure value, a current engine coolant temperature value, and a current intake manifold air charge temperature. An intercept of the total charge versus MAP reference function with an total charge axis (e.g. Y-axis intercept) is adjusted for current barometric pressure different from the reference barometric pressure, and the slope of the total air charge versus MAP reference function is adjusted for current engine coolant temperature and current manifold air charge temperature different from the reference engine coolant temperature value and the reference manifold air charge temperature value. An adjusted total charge is determined by engine control logic based on the adjusted intercept and the adjusted slope of the function. An estimated EGR charge can be subtracted the adjusted total charge to estimate air mass flow rate entering the engine cylinders.