GB1415961A - Means for effecting contact-free axially-stabilized and radially-centered positioning of a rotating shaft - Google Patents

Abstract

1415961 Bearings R DOLL and H BERNDT 3 Jan 1973 307/73 Heading F2 [Also in Division G3] A bearing system radially and axially supports a rotating shaft in magnetic bearings, each bearing having a ferromagnetic annular member attached to the shaft coacting with a stationary annular member to form a path for a stationary magnet and to radially centre the shaft. The axial position of the shaft is stabilized by an electromagnetic servoacting on the shaft in response to the sensed radial and axial deflection thereof, the radial correcting force being co-ordinated to the deflection of the shaft in its precessional movement. As shown, shaft 1, which is driven by turbine 2 or motor 2<SP>1</SP>, is supported at each end in magnetic bearings 11, each having a stationary, axially aligned permanent magnet 8 whose magnetic circuit comprises an annular ferromagnetic member 5 fixed to shaft 1, and stationary annular pole members 9, 7 spaced at distances a, b respectively from member 5. The axial and radial position of shaft 1 is measured by photocell 18 using light from source 16 and reflected by mirror 17. The photo-cell output is fed via PD controller 20 to vary the excitation of annular electromagnet 30, that has a laminated iron core, and which coacts with shaft 1 and a ferromagnetic flange 12, fixed to or integral with the shaft, to control the axial and radial shaft position. The bearing system may be supported by a tube having a natural frequency such as to attenuate orbital movements of the shaft.