SE300792B - - Google Patents

Abstract

1,055,768. Centrifugal separators. BECKMAN INSTRUMENTS Inc. April 13, 1964 [April 15, 1963], No. 15239/64. Heading B2P. In a stabilizing assembly for a centrifuge rotor 13, Fig. 1. (not shown), a member 51, Fig. 3, forming part of a bearing assembly 50 carried by the frame 11 of the centrifuge is rotatable coaxially of an axis of rotation passing through the centre of gravity of the rotor and its contents and is moved by means automatically responsive to rotation of the rotor below a predetermined speed at which wobbling of the rotor may occur so as to engage the rotor and restrain it to rotate generally about the axis or rotation, the member 51 being carried by means providing yielding resistance to lateral movements of the member to confine these movements within predetermined limits laterally of the axis of rotation whereby lateral movements of the rotor are damped. The stabilizing assembly comprises a Y-shaped bridge member 24 Fig. 2 (not shown), carrying fixed pins 29 and an adjustable pin 30 which are made to engage recesses in brackets 18, 19 secured to the frame 11 where the member 24 is located across an opening 12 in the top of the frame 11, proper orientation of the bridge being ensured by means of a liquid level 38. The member 24 is pivotable into and out of opening 12 by means of arms 42 secured at 43 to the member 24 and pivotable at 39 to the bracket 19. The member 51 is carried by the inner race of a ball bearing 53 the outer race of which is carried by an annular housing 55, e.g. made from acetal resin material, carried in turn within and laterally spaced from a housing 56. Relative rotation between the housings 55 and 56 is prevented by a pin and slot combination 57, 58. The housing 56 has a sleeve portion 59 slidably supported on a guide member 61 fixed to the bridge member 24 and having a conical end surface 63 adapted to receive a similar surface at the upper end of member 51, where the latter is in non-engageable position with the rotor 13. Housing 56 is yieldingly urged by a spring 64 to move member 51 to engage a cylindrical sleeve 15 mounted on the rotor. The undersurface of housing 56 being brought at the same time into frictional engagement with the upper surface of housing 55, thereby providing the yielding resistance to the lateral movements of the member 51. The member 51 is moved between advanced and retracted positions by spring-biased arms 72 engaging trunnions 75 on housing 56 and pivotable at 73. The arms 72 are actuated through links 81, 82 by the armature 78 of a solenoid 77 connected by leads to a wiring connector plug 84 to which is connected a relay 88 included in a speed control circuit 87. A speed transducer 86 detects the rotational speed of the rotor spindle 14 and feeds a signal to the circuit 87 to energize the relay 88 whenever the speed of rotation of the spindle is above a predetermined velocity. Energization of relay 88 causes deenergization of solenoid 77 whereby armature 78 is moved to the right and, with the aid of the spring 76 raises arms 72 upwardly to retract member 51. After a centrifuging operation, as the rotor slows down below the predetermined speed, the solenoid 77 is again energized and armature 78 is moved to the left to lower the arms 72 and hence the member 51 into engagement with the sleeve 15 on the rotor. The rotor spindle 14 is journalled in an oil-filled bearing 26 and is driven by means of a motor 34 through belt 32 and pulleys 31, 33 or through suitable gearing. The rotor is mounted in a chamber 17 including steel walls 21. 22 guarding against explosion of the rotor. The chamber 17, which is mounted on a base 28 supported on a fixed member 36 by springs 37, is provided with cooling evaporator coils 23 which control the temperature inside the chamber. The rotor temperature is measured by means of a thermistor 65 located within the sleeve 15 whose inside surface is blackened to provide a radiation black body chamber. The thermister is mounted in a holder 66 resting on a shoulder formed in the guide member 61. Radiation leakage is minimized by a blackened guard ring 67 fastened to the bottom of housing 56 and a, radiation shield 69 having a blackened under surface and carried by posts 71 depending from member 24.