GB1018886A - Automatic pressure oil control for pushing centrifuges - Google Patents

Abstract

1,018,886. Centrifugal strainers. ERSTE MASCHINENFABBRIK KARL - MARX STADT. VEB. Jan. 9, 1964, No. 1025/64 Heading B1D. [Also in Division F1] The filtering drum 2 of a centrifugal strainer is cleared by advance of a reciprocating pushing member 5, whose length and frequency of stroke are independently variable. High pressure oil from pump 17 is directed to one of annular grooves 8, 9 in oil feed bearing 7 surrounding the hollow shaft 1 and hence to one or other side of driving piston 6, depending on the position of reversing piston 16. Pre-control piston 13 is connected in parallel with piston 6 across the high pressure supply, and in the position shown piston 6 moves rightwards and piston 13 is pushed to its leftward position. Piston 13 thus switches a low pressure oil supply from pump 14 and conduit 31 to conduit 20 and initiates rightward movement of control piston 15. An adjustable regulating valve 23 on the discharge side of piston 15 limits its speed and while piston 15 is moving, driving piston 6 achieves and remains stationary in its rightward position. When piston 15 achieves its rightward position it switches the low pressure supply via conduits 28, 29 to move reversing piston 16 to its leftward position, Fig. 1 (not shown), in which it initiates leftward movement of driving piston 6, and the whole process is repeated in reverse. Adjusting regulating valves 22, 23 varies the durations of the leftward and rightward movements of control piston 15 and hence the "rest time" of pushing member 5 in each extreme position. The cycle repeats itself automatically as long as pumps 14, 17 are switched on; they may be a single pump with two delivery streams, or their motors may be interconnected for simultaneous switching on. For a strainer which discharges on one side only, as shown, valve 23 may be omitted, so that pushing member 5 "rests" only at its leftward position. The strainer could discharge at both ends, however. The rightward stroke of piston 6 ends when the inward end of bore 25, through which oil is discharging, is blocked by a bush 11. To vary the length of stroke, bush 11 is axially adjustable through an oblique slot 10, Fig. 3 (not shown), or one or more longitudinal slots, and carries a locking device 12. A bore 33 equalizes pressure across bush 11. Check valve 19 allows pressure to reach the right hand side of piston 6 even with bore 25 closed, Fig. 1 (not shown); valve 18 permits discharge with the other end of bore 25 closed (Fig. 2).