To detect a correct purge gas flow rate in consideration of concentration of evaporated fuel contained in purge gas.
An ECU 40 calculates reference differential pressure ΔPb from a map of intake pipe pressure Ps, differential pressure ΔPv between before a purge valve and after the purge valve, and differential pressure ΔP100 of air of 100%. In the ECU 40, the calculated reference differential pressure ΔPb is divided by the differential pressure ΔP100 of air of 100% to calculate a reference differential pressure ratio ΔPr, and then an evaporated fuel flow rate Fhc is calculated. The ECU 40 calculates a reduced flow rate ΔFre of the purge gas with respect to a purge gas flow rate F100 of air of 100% by using the reference differential pressure ratio ΔPb, and calculates a true purge gas flow rate Fp. The ECU 40 calculate an air flow rate Fair by using the calculated true purge gas flow rate Fp and evaporated fuel flaw rate Fhc.
ITAKURA HIDEAKI
KATO NAOYA
MATSUBARA TAKUJI
HYODO YOSHIHIKO
TOYOTA MOTOR CORP
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