Patent ID: 7487879

Claim:
A fuel filler cap comprising: an inner cap of a substantially cylindrical member; and an outer cap of a cover member mounted on the inner cap: wherein the outer cap includes an upper face portion having a circular shape, a skirt portion integrally extending downward from an outer circumference of the upper face portion, and a plurality of wedge-shaped projections having a triangular section formed circumferentially intermittently on an inner face of the skirt portion; wherein a pressing plate has a circular shape, as viewed in a top plan, and has a smaller diameter than the internal diameter of the skirt portion; wherein the inner cap includes a supporting plate having a circular shape, as viewed in a top plan, and having at least the number of annular slants formed radially downward and obtained by chamfering a peripheral edge of an upper face thereof intermittently by at least in a positional relation corresponding to the wedge-shaped projections, a seal ring fitted between a lower face of the supporting plate and an outer face of an inner cap body, and a plurality of annular grooves defined by the annular slants of the supporting plate and by a lower face of the pressing plate laid over the supporting plate; and wherein the pressing plate and the supporting plate are provided with a plate engagement means for turning integrally in an opening/closing direction of the fuel filler cap and for releasing an engaged state of the pressing plate with the supporting plate when a releasing load is applied upward to the pressing plate, said wedge-shaped projections are fitted to the plurality of annular grooves engagement holes are formed between the pressing plate and supporting plate in which an upper surface of the annular slants and a lower surface of the wedge-shaped projections slidably contact with each other so that an external force applied transversely with respect to the outer cap is converted to said upward releasing load and an external force applied downwardly with respect to the outer cap is converted to a detaching force which makes the wedge-shaped projections slip down along the annular slants and detach from the annular grooves, engagemnet holes are formed between the pressing plate and supporting plate.