The invention resides in an arrangement for limiting the fuel level in a fuel tank with a flap valve disposed at the inner end of a filler tube and having a valve flap which can be closed by a four link crank of breech mechanism utilizing a float by which the flap can be closed when the liquid level in the tank reaches a certain level by way of a coupling rod which is linked to a crank arm mounted on the valve flap support shaft.
DE-PS 69 7551 shows such an arrangement wherein the tank filler pipe is provided with a throttle flap, which is controlled by a float. The throttle flap fully or partially closes the filler pipe when the float is lifted by the rising liquid level at the end of the tank filling procedure. The float and the throttle flap are part of a centered linear crank breech mechanism. The various drive elements are so coupled that, for each position of the float, there is a specific corresponding position of the throttle flap. As a result, the filler pipe is again opened to the full extent only when the liquid level in the tank has fallen sufficiently that the float is no longer floating on liquid, that is, when it does not generate any buoyancy any more. With relatively flat tanks as they are used in motor vehicles, this has the disadvantage that the throttle flap keeps the tank or rather the filler pipe closed for a relatively long period and accordingly prevents the filling of a partially emptied tank.
In addition, fuel is backed up in the filler pipe of such an arrangement until the float opens the throttle flap when the liquid level has finally fallen sufficiently. With a movable tank, at least part of the fuel backed up in the filler pipe can be lost through the filler pipe opening by swishing movements for example.
It is therefore the principal object of the present invention to provide an arrangement which prevents over-filling of a tank and which permits refilling of a tank already after consumption of a relatively small amount of fuel such as several percent of the tank content. The arrangement should require few movable parts and should be service-free and operate safely. In addition, the arrangement should not be able to generate noises when installed in a movable tank such as in a motor vehicle tank. Also the filler pipe should not be able to spill any backed up liquid out of the filler opening after the filling procedure has been completed.