| 摘要 |
(57) A bellow-type pump comprises a plurality of bellows (51) to (54) grouped radially about the drive axis and driven simultaneously so that the torque is applied uniformly. Asymmetrical loading of the bellows, which reduces their service life, is prevented by improved coupling of the eccentric movement of the drive shaft (34) with the bellows. The outlets (62) from the individual bellows can be connected in parallel or in series, as desired, so that a greater delivery volume or higher delivery pressure can be attained, depending on requirements. The pump housing (1) consists of a double-cross piece used as an assembly unit in ultrahigh vacuum technology. To ensure complete evacuation of the pump, for example to allow subsequent introduction of ultrapure gases, spring-loaded valves (82) which block the direction of flow are maintained temporarily in an open position during normal operation. To this end, the closure bodies of the valves are made from a magnetic material and can be influenced by a magnet (84) mounted on the outside of the pump housing (1, 73), which is made from non-magnetic material. The valve returns to its closed position immediately the magnet (84) is brought into, and possibly stopped in, a remote position.
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