Closure system for fuel tank filler neck and method for opening said filler neck

The shutter system for the top of a fuel tank filler pipe consists of a shutter (10) that is opened automatically by the pressure of a fuel dispenser nozzle and closed by a spring when the nozzle is removed. The shutter is locked in the closed position by a plate (8) and ring with a bayonet coupling, and released when the access door to the fuel filler is opened.