| 摘要 |
A dispensing pump is characterized by an elastomer bulb configured as a cup and having a tubular neck portion extending from its base. The cup portion is inverted in a pump housing with the neck extending upwardly from the center of the cup base into a stem member where it concentrically and resiliently engages a nipple. The rim of the cup portion is positioned to overlie a dip tube inlet into the housing. In its quiescent position the bulb is slightly longitudinally compressed by forcing the stem, neck and center of the cup portion into the bulb chamber, thereby forming a convolution at the periphery of the cup base. The convolution provides a positive seal of a vent passage which is open only during pump actuation. Actuation is effected by pushing the stem further into the cup, which action is aided by a spring snapping effect in the bulb, thereby forcing fluid from the pump chamber up through the neck and around the nipple. Relaxation of the stem permits the spring action to restore the bulb to its quiescent state while the cup rim is drawn into the chamber to unblock the dip tube and draw fluid into the chamber.
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