Patent ID: 7281639

Claim:
A fuel cap comprising a closure to be secured in an oil filler port attached to an inlet of a feed oil pipe, and a handle for turning the closure, the oil filler port being provided on an inner side surface thereof with a plurality of circumferentially extending ribs intermittently, the closure including: a closure body having a head portion to be turned, a trunk portion extending downward from the head portion, and an annular trunk surface with downwardly extending stopper projections formed on a side surface of the trunk portion, a seal ring which is fitted around the trunk portion so that the seal ring is fitted between a lower surface of the head portion and an upper portion of the annular trunk surface, and which pressure-contacts with an inner side surface of the oil filler port in radius direction from an inner side thereof, a sleeve with annular shape having on an inner side surface thereof an annular sleeve surface provided with stopper recesses into which the stopper projections are fitted, and on an outer side surface thereof downwardly extending anti-rotation projections which are fitted in clearances between the ribs, and adapted to lift up the seal ring, a coiled spring urging the sleeve upward, and an engagement member having engagement projections adapted to be turned through the clearances between the ribs of the oil filler port and thereby engaged with the ribs from a lower side thereof, and formed by integrally assembling these parts in the mentioned order; the holding of the seal ring by the lower surface of the head portion of the closure body and an upper surface of the sleeve becoming: tight when the stopper projections of the closure body are fitted in the stopper recesses to cause the sleeve to be lifted by a force of the coiled spring, and loose when the stopper projections are disengaged from the stopper recesses and run on the annular sleeve surface to cause the sleeve to be pressed down against the force of the coiled spring.