Method for estimating and controlling the intake efficiency of an internal combustion engine

A method for calculating the mass of an overlap gaseous flow (MOVL), in the case of exhaust gas internal recirculation (EGRi), wherein the exhaust pressure is higher than the intake pressure, or in the case of scavenging (SCAV), wherein the intake pressure is higher than the exhaust pressure,

• said overlap gaseous flow (MOVL) being the flow which flows, in overlap conditions, through the intake valve and the exhaust valve of a cylinder of an internal combustion engine comprising a number of cylinders, wherein each of the cylinders is connected to an intake manifold from which it receives fresh air through at least one respective intake valve, and to an exhaust manifold into which it introduces the exhaust gases generated by the combustion through at least one respective exhaust valve, wherein the at least one intake valve is driven so as to vary the lift (H) of the intake valve in controlled manner,
• said overlap condition being a condition in which said intake valve and said exhaust valve are both at least partially open,
• wherein the method comprises:
• calculating the mass of the gaseous flow (MOVL) which flows through the intake valve and the exhaust valve on the basis of the relation:
• MOVL=PERM*β(P/P0,n)*P0/P0_REF*(T0_REF/T0)1/2/n,
• where PERM is the hydraulic permeability associated to the overlap condition;
• n is the engine speed;
• β(P/P0,n) is a compression factor of a flow through an orifice, depending on the ratio between the pressures downstream and upstream of the orifice and on the engine speed (n);
• and where:
• under a condition of internal recirculation of the exhausted gases, P0 is the exhaust pressure, P0_REF is a reference exhaust pressure value and P is the intake pressure, T0 is the temperature of the exhaust gases, T0_REF is a reference value for the temperature of the exhaust gases T0;
• and/or
• under a condition of scavenging, P0 is the intake pressure, P0_REF is a reference intake pressure value and P is the exhaust pressure, T0 is the temperature of the intake gases, T0_REF is a reference value for the temperature of the intake gases;
• and wherein said hydraulic permeability (PERM) is calculated based on a first function and a second function, wherein the first function depends on the engine speed (n) and on the duration of the overlap condition (OVL) during which the intake valve and the exhaust valve are simultaneously opened, and the second function depends on the lift (H) and the engine speed (n).