| 摘要 |
PROBLEM TO BE SOLVED: To reduce an amount of vaporized fuel flowing out from a fuel tank to the external part of a fuel tank with low energy by a method wherein, when it is decided that concentration of vaporized fuel in air in a space above a fuel liquid level in the fuel tank is below predetermined concentration, concentration of the vaporized fuel is increased. SOLUTION: When vaporized fuel concentration detected by a vaporized fuel concentration sensor 27 during operation of an engine body 19 is below predetermined concentration, a heater in an auxiliary fuel chamber 13 is operated. Fuel is heated for vaporization and vaporized fuel concentration in a fuel tank 1 is increased and a pressure in the tank is increased. Along with the increase of a pressure in the tank, a diaphragm valve 46 is opened and gas containing air and vaporized fuel is discharged to a char coal canister 29 and vaporized fuel concentration in the fuel tank 1 is increased. Thereafter, when vaporized fuel concentration exceeds predetermined concentration, operation of the heater is stopped and the diaphragm valve 46 is closed. Thus, vaporized fuel is prevented from flowing out from the fuel tank 1.
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