A tether mechanism includes a rotatable ring rotatably mounted to a ring mounting element, a linking member and a rotatable connector. The linking member has a long linking member main body, a first support end that is formed at one end of the linking member main body and is connected to the rotatable ring and a second support end connected to the fuel supply lid. The rotatable connector has a U-shaped connector, and the linking member main body can rotate relative to the rotatable ring around the longitudinal axis thereof.