METHOD OF CALCULATING GAS PRESSURE ON THE BASIS OF PRESSURE IN INTAKE LINE OF INTERNAL COMBUSTION ENGINE

PROBLEM TO BE SOLVED: To provide a method of calculating gas pressure and contamination degree of an air filter surely with a sufficient accuracy on the basis of gas pressure measured in an intake manifold of an internal combustion engine. SOLUTION: The method of calculating gas pressure calculates gas pressure on the basis of a suction pressure measured at the downstream of the air filter 4 in a suction line 3 of the internal combustion engine 2 and air mass flow rate measured at the downstream side of the air filter 4, and optionally on the basis of suction air temperature. According to the present invention, calculation of gas pressure and calculation of contamination degree of the air filter 4 can be separated from each other by standardizing the air mass flow rate thus measured into two predetermined values. Further, a characteristic curve on the contamination degree of the air filter 4 is used as a function of differential pressure calculated at the predetermined air mass flow rate, and a characteristic diagram on the contamination degree of the air filter 4 is used as a function of standardized air mass flow rate and measured differential pressure. COPYRIGHT: (C)2003,JPO