| 摘要 |
The present invention relates to, among bellows pumps for transporting a liquid with using a bellows which axially extends and contracts, a so-called internal-liquid type bellows pump in which an air chamber is formed outside a bellows and a liquid to be transported is sucked into the bellows. In order to prevent a pump bellows, a piston or coupling plate, and a shaft coupling them from being deviated from the same axis, prolong the life period of the pump, maintain the pump performance for a long term, and realize compactification and cost reduction of the pump, an external thread is formed on the outer face of one end side of the shaft, an engagement head is formed on the other end, a bottomed cylindrical shaft screwed portion which is projected from a center portion of the bottom into the pump bellows on the same axis, and which has an internal thread on an inner face is disposed in a bottomed cylindrical pump bellow, and the one end side of the shaft is directly coupled with a center portion of the pump bellows by thread joining.
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