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Abstract

A pumping device for a liquid container comprises a bellows body with upper and lower plates. The upper plate has a suction port adapted to be communicated with the atmosphere, , and the lower plate has an exhaust port adapted to be communicated with an interior of the liquid container a suction valve is adapted to open and close the suction port; and a bellows return spring is adapted to expand the bellows body. A stop valve assembly is arranged in the bellows body and forms a bypath for communicating the interior of the bellows body with the interior of the container. The stop valve assembly comprises a flap valve adapted to allow the air only to flow from the bellows pump to the container through to air port during operation of the bellows body, and a valve structure for closing the bypath, the valve structure being operated under the conditions synchronized with contraction and expansion motion of the bellows body in such a manner that is closes the bypath just after starting the contraction of the bellows body but opens the same just before finishing the expansion of the bellows body. The stop valve assembly may be replaced with one comprising a case having a main path and a bypath for communicating the interior of the bellows body with the interior of the container, a stop valve arranged in the main path so that it allows the air only to flow from the bellows body to the container, a valve structure arranged in the bypath, and a device for operating the valve structure.

First Claim