| 摘要 |
The invention relates to a piston (4) for a container (1) with a cylindrical inner surface, where the container is provided with a sealing upper seal (3, 6) through which at least one piston rod (5) extends in a slideable fashion. The piston is attached to the lower end of the piston rod and the container has a lower sealable opening (2). The main portion of the upper surface of the piston is convex, while the main portion of the lower surface of the piston is less convex than the upper surface. This makes the piston act as a check valve, which lets liquid pass only when the piston is moved in the container in one direction. In one embodiment the upper surface of the piston extends to the piston rod (5) and is attached at it. This gives the piston a more pronounced check valve characteristic. In another embodiment, a recessed channel (9) may extend on the upper surface of the piston from the periphery of the piston towards its centre. This channel further enhances the check valve characteristics of the piston. The invention further relates to a container (1) with a cylindrical inner surface, typically a syringe, with such a piston. |
