| 摘要 |
A piston-cylinder assembly in which the piston includes two piston heads connected together in spaced relation by a stem and cooperable with two portions of the cylinder, dividing the cylinder into a working chamber on one side of the first piston head between it and the end wall of the cylinder, a drive chamber on the opposite side of the second piston head communicating with the drive, and an intermediate chamber between the working chamber and drive chamber. The first piston head defines a clearance seal with respect to the first portion of the cylinder, and the second portion of the cylinder guides the reciprocatory movements of the piston. The intermediate chamber includes a semi-permeable seal between the cylinder and piston, which seal is permeable by gas but impermeable by liquids, to thereby prevent the passage of liquid from the drive chamber through the intermediate chamber to the working chamber. |
