| 摘要 |
A rotor arrangement (10), particularly a shaft suspended in a magnetic bearing arrangement having an active axial magnetic bearing (12), includes an axial shaft displacement sensor (26) and a displacement rate transducer (32) which co-operates with an axially exposed face (31) of a ferromagnetic shoulder feature (30) of the shaft, or a functional element carried on it. The transducer (32) comprises an annular permanent magnet core including an annular pick-up coil disposed in groove (34) between a pair of annular permanent magnet pole pieces (35, 36), one pair of poles (37', 38') being joined by an annular keeper and the other poles (37, 38) separated from the shoulder face by air gaps (39, 40) defining a magnetic flux path through the shoulder feature. Changes in the flux density resulting from changes in air gap length with shaft displacement induce a coil voltage related to the rate of displacement. Although the coil is disposed radially outwardly from the rotation axis (16) where the surface is translating past the hole pieces at a high speed, the annular magnet is unaffected by any irregularities which locally alter the air gap, unlike other transducers.
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