EVAPORATIVE FUEL DISPOSAL DEVICE

摘要

PROBLEM TO BE SOLVED: To detect a large quantity of leak with excellent precision. SOLUTION: An evaporative fuel disposal device for an internal combustion engine comprises a fuel tank; a charge passage to interconnect the fuel tank and a canister; a purge control valve situated in a purge passage to interconnect the canister and the intake pipe of the internal combustion engine; an evaporative fuel discharge suppression system having a vent shut valve to open and close a release port situated at the canister and releasing an internal part to the atmosphere; an internal pressure sensor to detect a pressure in an evaporative fuel discharge suspension system; an internal pressure monitoring means to decide that leak occurs in the evaporative fuel discharge suppression system when a fluctuation of a pressure in the evaporative fuel discharge suppression system detected by the internal pressure sensor is small; a leak check means to decide the presence of leak by the change of the internal pressure sensor when the evaporative fuel discharge suppression system forms a closed system based on the output of the internal pressure sensor; and a large quantity of leak deciding means to decide the presence of a large quantity of leak when it is decided by the internal pressure monitoring means that leak is present and a change of a pressure momentarily occurs during decision by the leak check means.