To provide an overfilling prevention device for a DME fuel tank, capable of operating accurately and stably so that the DME fuel tank is not filled with DME fuel beyond the maximum filling level of the DME fuel tank.
A diaphragm type overfilling prevention device 2 is configured in such a manner that a diaphragm 7, which is provided on the rear side of a main outlet 16 from which a DME fuel flows into the DME fuel tank, and forms a variable closed region 21 which is separated in a sealed manner from the main outlet 16 side, is formed by stacking a synthetic rubber plate 31 and a metallic plate 33 in the thickness direction of the diaphragm, with the metallic plate 33 provided on the variable closed region 21 side. The configuration enables the diaphragm 7 to operate accurately and stably even if filling of the tank with the DME fuel and consumption of the DME fuel are repeatedly performed, and also enables both a function of filling the tank with the DME fuel and a function of preventing overfilling of the tank with the DME fuel to be stably performed for a relatively long period.
IWATSUKI KEIJI
Yu Yamamoto
Yasutoshi Iwata