EVAPORATED FUEL TREATMENT DEVICE

PROBLEM TO BE SOLVED: To provide an evaporated fuel treatment device applicable even to an idle stop vehicle, and capable of preventing the ratio from becoming the rich air-fuel ratio by evaporated fuel generated from a fuel tank. SOLUTION: This evaporated fuel treatment device has a purge valve for opening and closing a pipe for communicating a canister for sucking the evaporated fuel generated in the fuel tank with an intake passage of an engine, and has an emission deterioration determining means (Step S37) for determining whether or not exhaust emission is deteriorated at that time, by reducing a corresponding quantity of an estimated fuel desporption quantity from fuel supplied to the engine, by estimating the fuel desorption quantity desorbing from the canister by using a canister mode, when controlling the purge valve for opening on the basis of the target purge ratio set so as not to deteriorate the exhaust emission, and a fuel excessive evaporation determining means (Step S38) for determining that an evaporated fuel quantity being generated in the fuel tank is excessive, when determining the deterioration in the exhaust emission by the emission deterioration determining means. COPYRIGHT: (C)2008,JPO&INPIT