| 摘要 |
<p>A vacuum pump assembly which comprises at least two cylinders (4,5) of different diameters and arranged coaxially relative to each other to define an annular space (6) therebetween and a helical member (7) positioned within the space to define a helical path between the cylinders (4,5) wherein means are provided to effect rotation of the cylinders (4,5) relative to the helical member (7), or vice versa, about their longitudinal axis. <IMAGE></p> |
