| 摘要 |
High velocity vacuum pump, such as turbomolecular pump, drag pump, centrifugal pump or the like, comprising a stator (10) and a rotor (18,43,53), which is axially and radially suspended with respect to the stator (10) by magnetic bearings (27). The vacuum pump may comprise two at the same rotor provided, parallelly acting pump portions, each one comprising two pumping steps. The rotor may be cylindrical and rotates around an inner stator shaft and within an outer stator portion. In that way, one pumping step (22) is formed between the inner stator shaft and the rotor and another pumping step (24) between the outer stator portion (10) and the rotor. The magnet bearing comprises at least one rotation symmetric magnet (27) and is disposed to give rise to a rotation symmetric magnetic field which is centered around the rotational axis. When and only when the rotor tends to leave the predetermined path, the magnetic field generates induced eddy currents in the rotor, which give rise to restoring stabilizing forces. |
