| 摘要 |
The invention refers to an apparatus for a controlled delivery of a liquid preparation from a cylindrical liquid container, which has a liquid outlet at its front end and a movable wall, which acts like a piston, at its rear end. The driving force acting on the movable wall for expelling the liquid from the container is generated by means of a piston rod in connection with a piston, which by the action of the atmospheric pressure is urged into a space where a vacuum has been established. According to the invention, the amount delivered can be varied according to different modes by providing an auxiliary force which acts on the piston during the initial stage of its movement into the vacuum space.
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