Patent GB-1425620-A (GB)
Title: Centrifuges
IPC: F16C17/10
Filed: 1973-06-11
Abstract: 1425620 Supporting and damping centrifuge bowl COMMISSARIAT A L'ENERGIE ATOMIQUE 11 June 1973 [29 June 1972] 27709/73 Heading B2P [Also in Division F2] A centrifuge comprises a vertically disposed centrifuge bowl 1 supported by a step bearing 3 of which the male portion or pivot 2 is secured indirectly to the bottom portion of the bowl and the female portion or cup 4 rests on damping means which include: a hollow, cylindrical, flexible shaft 5 terminating at its top in a reservoir chamber 28 containing oil for the bearing, the female cup 4 of the bearing being formed as a spherical recess in the bottom of the chamber; a hollow conical damping support 6 surrounding the shaft 5 which is inserted into its lower end; a substantially cylindrical casing 8 which is secured to the base of the support and to the top of the shaft so as to enclose the shaft-support assembly in leak-tight manner and to form, on the one hand, between the shaft and the support and on the other hand, between the support and the casing a closed space filled with damping oil; and means 15, 16 provided in the hollow portion of the shaft 5 for ensuring laminar flow of a cooling fluid supplied at 17. To ensure leak-tightness, weld fillets 7, 9, 10 are provided between the shaft 5 and the support 6, between the casing 8 and the support 6 and between casing 8 and the shaft 5. The casing 8 is made rigid by the provision, of bulges 11-13 and is provided with a bellows-type portion 14 at the level of the nodal point about which the shaft 5 oscillates. The cylindrical hollow member 15 and the axial deflector 16, joined to the top projecting portion of the shaft, define a hairpin path for the cooling fluid e.g. alcohol, which is discharged at 18. The damping oil which has a viscosity varying slightly with temperature is introduced through a duct 19 and is maintained at constant pressure by means of a compensation bellows element 20. The female cup 4 is formed in a member 22 and is extended by a cylindrical portion 23 to ensure radial stiffness of the pivot 4. A ridge 26 on the pivot prevents oil contained in the chamber 28 up to the level 27 from flowing up the pivot when the latter rotates. The oil is supplied to the chamber through a pipe 29 and is prevented from rotation in the chamber by radial fins 31. The oil has a viscosity which varies substantially with temperature. Thermocouples 32 are provided in the member 22 to check the temperature of the bearing The chamber 28 is surmounted by a spherical wall 33 having a grooved outer surface which cooperates with the smooth undersurface 36 of a flared portion of the lower end of the 'bowl to provide a Holweck-type pump which forces back to the interior of the chamber any oil tending to escape therefrom. Spiral grooves are formed in the spherical portion of the pivot 2 to provide pumping effect so as to pressurize the oil film between the pivot and the oup. The bowl 1 is driven by a hysteresis motor 37 whose magnetic windings 38 act as a magnetic element 39 mounted within a hollow shaft 40 secured to the bowl. The motor is fixed by a frame member 41 on the lower portion of the damping support 6 and is separated from the latter by a ceramic heat insulator 42.