A structure of an opening portion of a fuel tank, comprising:
- a fuel tank main body made of a thermoplastic synthetic resin having at least an outer layer, an inner layer and a middle layer therebetween;
- an opening portion being integrally formed with the fuel tank main body, the opening portion including an opening face connected to the fuel tank main body through a cylindrical portion, the cylindrical portion extending from the fuel tank main body toward an outer side of the fuel tank main body;
- the cylindrical portion including a laminate with layers of a thermoplastic synthetic resin on upper and lower sides thereof and having an outer face arranged parallel with the opening face of the opening portion;
- the cylindrical portion further including a folded portion extending from a front end of the cylindrical portion in a direction of enlarging diameter of the cylindrical portion toward the outer side of the fuel tank main body and folding in a hairpin shape in a direction toward a center of the opening portion, at least a portion of the folded portion of the cylindrical portion including a compression portion compressing the opening portion from a direction orthogonal thereto, the at least a portion of the folded portion of the cylindrical portion being more thinly walled than other portions of the folded portion;
- a lid member covering the opening portion of the fuel tank main body;
- a lock ring being integrally embedded in the outer layer of the cylindrical portion, the lock ring being made of metal and having a ring shape and lock holes, the ring shape of the lock ring including an upper face portion with the lock holes, the upper face portion having a plane in parallel with the opening face of the opening portion of the fuel tank main body for pressing a surrounding area of the lid member against the opening portion of the fuel tank main body, the lock holes respectively including a wide width portion and a narrow width portion extending in a circumferential direction, the lock ring including a stepped portion bent in steps from the upper face portion to a lower side thereof and terminating in a lower vertical wall portion, the lower vertical wall portion being folded to a lower side thereof in steps from the upper face portion, and the lower vertical wall portion being integrally embedded in the outer layer of the cylindrical portion of the fuel tank main body;
- and
- a lock plate securing the lid member to the opening portion of the fuel tank main body, the lock plate being made of metal and having a ring shape and engaging claw portions, the lock plate having an upper flat plate portion having a plane in parallel with the opening face of the opening portion of the fuel tank main body, the engaging claw portions include a bent L-shape extending from a front end of the lower vertical wall portion of the lock ring in a direction toward the center of the opening portion, and the engaging claw portions engaging with the lock holes arranged in the upper face portion of the lock ring;
- wherein the engaging claw portions of the lock plate engage the lock holes of the lock ring and the lid member is clamped against the opening portion by the lock plate for closing the opening portion of the fuel tank main body.