LU40427A1 - - Google Patents

Abstract

918,750. Bearings. COMPAGNIE DE CONSTRUCTION MECANIQUE PROCEDES SULZER. Aug. 1, 1961 [Aug. 3, 1960], No. 27961/61. Class 12 (1). [Also in Group XXXV] A device for magnetically centring and driving a rotor 3 of a rotating machine comprises a centring magnetic induction circuit coaxial with and adjacent to said rotor; means for producing a magnetic flux in the magnetic circuit of said centring inductor, which is provided, on the side adjacent the rotor, with polepieces having concentric rings or rims. The rotor has, on the side facing the magnetic circuit of the centring inductor, a magnetic circuit comprising inner and outer concentric rims which face the corresponding rims of the centring inductor. The rims have sharp-edged concentric ribs so that magnetic flux produced in the centring magnetic induction circuit closes through the magnetic circuit of the rotor and causes the centred rotor to be maintained on the axis of the centring magnetic induction circuit. In an embodiment, a magnetic clutch, Fig. 1, has a driving-shaft 1 with an integral rotor 2 and has a floating driven rotor 3 integral with a compressor wheel 4. The shaft 1/rotor 2 are enclosed in a casing 6 and the rotor 3/wheel 4 are in a casing 5. Thus, the driven rotor may be rotated in any ambient medium while being insulated from the other medium containing the driver rotor. The shaft 1 is supported by plain journal bearings 9, 10 and a thrust bearing 8 and carries an annular magnetic induction circuit 12 wherein a stationary field winding 13 is located to produce a magnetic flux which transmits the torque between the rotor 2 and the rotor 3. The rotor 2 has teeth 14 in an external rim and teeth 15 in an internal rim, the teeth being separated by an annular member 16 of non-magnetic material. The rotor 3 has a first annular magnetic circuit 17 carrying an external toothed rim 18 and an internal toothed rim 19. Teeth 14, 15 of the rotor face rims 18, 19 of the rotor 3 respectively, a partition 7 of the casing 6 being therebetween. The rotor 3 carries a second annular magnetic circuit 21 which co-operates with a centring magnetic induction circuit 22 carried by a portion 23 of the machine. The circuit 22 comprises rings 24, 25 of magnetic material interconnected by an annular crosspiece 26 of non-magnetic material, an annular field winding 27 being located between the rings 24, 25. The rings 24, 25 have external and internal pole rims 28, 29 which have circular ribs with sharp edges. The second magnetic circuit 21 of the rotor 3 has external and internal rims 31, 32 with sharp-edge ribs. The rotor 3 is centred by energizing the field winding 27 to generate a magnetic flux which closes through the rings 24, 25, the second magnetic circuit 21 of rotor 3 and the portion 23 of the machine. The flux is concentrated in the ribs of rims 28- 32 to accurately centre the rotor 3 relative to the axis " X "-" X " so that the overall reluctance of the magnetic circuit is a minimum in this position. The second magnetic circuit 21 of the rotor 3 has a peripheral skirt 33 which engages an annular bearing surface 34 of a housing 35. The surface 34 may be of conical or spherical shape and is subjected to pressure by the rotor 3, the pressure being caused by the magnetic fluxes. The pressure is adjusted by an auxiliary magnetic induction circuit 36 having an annular shield 37, the inside of which contains a field winding 38. The rotor 3 has a ring 39 of magnetic metal through which the flux generated by the auxiliary magnetic induction circuit 36 closes, so that the ring 39 is subjected to an axial attraction force in the direction of the induction circuit 36. The axial attraction force is adjustable by varying the excitation of the field winding 38 so as to partly compensate for the pressure of the rotor 3 on the surface 34. In an alternative embodiment, not shown, the magnetic flux produced by the centring magnetic induction circuit serves also to transmit torque between the driving rotor and the floating driven rotor.