US1950297A - Full-speed centrifuge - Google Patents

Description

March 6, 1934. K, EGG 1,950,297

FULL SPEED CENTRIFUGE Filed Feb. 25, 1950 6 Sheets-Sheet l March 6, 1934.

K. EGG

FULL SPEED CENTRIFUGE Filed Feb. 25, 1930 6 Sheets-Sheet 2 March 6, 1934. K. EGG

FULL SPEED CENTRIFUGE 6 Sheets-Sheet 3 Filed Feb. 25, 1930 March 6, 1934. K, EGG 1,950,297

FULL SPEED CENTRIFUGE Filed Feb. 25, 1930 6 Sheets-Sheet 4 Olli z4f a Z1 56 im Z0 lg it 0 l z Z0 z8 3 IZ 7; 5 s 6 4,

March 6, 1934. K EGG 1,950,297

FULL SPEED CENTRIFUGE Filed Feb. 25, 1930 6 Sheets-Sheet 5 K. EGG

FULL SPEED CENTRIFUGE March 6, 1934.

Filed Feb. 25, 1930 6 Sheets-Sheet 6 Patented Mar. 6, 1934 UNITED STATES FULL- SPEED CENTRIFUGE Karl Egg, Cham, Switzerland Application February 25, 1930, Serial No. 431,324

In Germany 5 Claims.

This invention relates to improvements in or relating to full-speed centrifuges.

Various constructional types of centrifuges are already known, which operate continuously and in which the high speed rotating drum can be discharged by various devices without altering the speed of the drum.

Thus, for example, centrifuges are known, in

which the two halves of the drum are pressed against one another by hydraulic pressure whilst the centrifuge is in operation and which are discharged by releasing the pressure so that the two halves of the drum can separate whereby a iissure or slot-shaped opening is formed along the greatest circumference. The foreign bodies deposited by centrifugal force on the inclined walls of the drum escape through the opening thus formed. The disadvantage of these known centrifuges, aside from the requisite high pressure, which must be maintained continuously during the whole working period, in order to keep the two halves of the centrifuge drum tightly pressed together, resides in the fact that the two halves of the rapidly rotating drums must be displaced on their axes to effect the discharge. Owing to this displacement the equilibrium of the drums is easily disturbed and for this reason drums of this kind have hitherto not been allowed to run at a speed even approaching that of a modern high speed centrifuge.

Centrifuges are also known, both with vertical and with horizontal spindles, which are provided on their periphery with a number of Valves, which, in order to discharge the drums are, however, opened inwards by pressure from the outside by means of devices such as wedge-shaped cam rails disposed outside of the drums. These centrifuges can, however, operate only at low peripheral speeds, since, even at only slightly increased peripheral speeds, any rollers or pins of the valves are simply knocked off. Owing to the low peripheral speed occasioned by the discharging device, centrifuges of this type find no practical application, because their clarifying power is insuicient, since, as is known, the centrifugal force and consequently also the speed of subsidence of the foreign bodies in the liquid to be clarified are proportional to the square of the peripheral speed.

Centrifuges with vertical or horizontalspindl'es are also known which are provided with drums inclined at their circumference towards the centre and which operate inclined slide valves by means of lever devices disposed outside of the spindles. These drums, however, owing to their construction cannot be made round but only with as many surfaces as there are slide valves. The slide valves are not radial but are inclined according to the chosen slope of the drum Walls. The centrifugal force is, therefor, not capable of March 6, 1929 electing a secure closure and the greatest disadvantage of this type of drums is that they also cannot rotate at great speed because the masses of the rods cause the slide valves to become fixed and the rods to be torn oli. Further, in the case of drums which are not round but have many angles, a uniform deposition of the foreign bodies to be separated by centrifuging is impossible so that even at comparatively small speeds the equilibrium of the drum becomes disturbed. These types of centrifuges also have, owing to their low peripheral speed, little clarifying power and are, therefore, useless in practice.

Centrifuges with vertical or horizontal spindles are also known which are provided with drums inclined inwards and which possess on their extreme periphery a number of Stoppers or valves which in order to discharge the drums are pressed inwards' either automatically or by means of eX- ternally disposed lever devices operated by hand. These drums also cannot rotate at a high peripheral speed since the mass of the rods is so great that even at a comparatively low speed these rods will be torn off. These kinds of drums provided with valve or stopper discharging devices have, moreover, the great disadvantage that these comparatively small valves whilst being capable of allowing liquid to discharge from the drum do not, however, permit the escape of the sludgev deposited on the drum walls by the centrifugal force from the liquid to be clarified, which sludge, in the case of high speed drums which are sometimes rotated at a peripheral speed of and more metres per second, is as dry or solid and tough as glaziers putty. In the case of drums of this kind, therefore, even if they could rotate' at a high peripheral speed, which, however, is technically impossible, only a fraction of the sludge deposited can be discharged. Further the discharge would never be uniform so that the equilibrium would in any circumstances be disturbed and, therefore, a high peripheral speed could never be attained owing to the drum running in an unsteady manner.

Centrifuges with vertical or horizontal spindles are also known which are provided with drums inclined inwards andv which for the purpose of discharging are provided at their greatest circumference with a number of Stoppers or'valves which with their rods areV pressed outwards by the centrifugal force and which for the purpose of discharging are drawn inwards by mechanical devices. These mechanically operated devices are disposed within the drum but outside of the spindle and are adapted to be operated by hand. These arrangements therefore, relate not to an automatically regulated discharge but to a discharge which must be effected by hand by an attendant operator. These centrifuges also, however, owing to their construction, cannot rotate at a high peripheral speed and further the disposition of Stoppers or valves is intended only for comparatively watery impurities, for example for purifying cane sugar juice, and a solid sludge which has a tenacity resembling glaziers putty,

either cannot be discharged from the drums, or

can be only partially discharged. Further thedischarge would be so irregular thatthe drumsv would in any circumstances lose their equilibrium and this circumstance in itself prevents the drums from rotating at a high peripheral speed.

The device characteristic of the present invention for automatically discharging the centrifuge drum of a continuously operated high power` speed centrifuge, enablesthe drum even when rouniformly expelled by the high centrifugal force f developed by the drum rotating at very high speed.

Since as already mentioned the centrifugal force increases as the square of the peripheral speed and the discharge device is so constructed cu l,

Y A-k-B (Figure 1).

that the equilibrium of the drum cannot be disturbed even at the highest possible peripheral speed, it is possible in the drum according to this invention to raise the number of revolutions of the drum up to the` limit of the physical proportions which the material employed for construction of the centrifuge drum permits.

The object of the invention is illustrated by way of example in the accompanying drawings.

Figure 1 is a vertical cross section of the upper half of the machine.

Figure 1a is a vertical cross section of the lower half of the machine.

Figure 2 is a rear View with the lid removed,

Figure 3 is aV horizontal section along the line Figure 4 is a View in side elevation of the drum.

Figure 5 is a cross section through the drum along the line'C-D (Figure 1).

Figures 6, 7 and 8 are detail sectional views on an enlarged scale showing certain parts of the operating mechanism more clearly. Figure 7 is a section on the line A-B through the parts shown in Figure 6, while Figure 8 shows the same parts as Figure 6, but in a dii-ferent position.

The centrifuge is driven by a transmission, preferably by an electric motor l, which is mounted on a base plate, which is constructed in one piece with the closure plate 35. An endless belt transmits the power to the pulley 3. A belt stretcher 2 keeps the driving'belt under the desired tension. The driving belt pulley 3 is loose on the lay-shaft 6 of the centrifuge. A friction coupling having cheeks i (Figure 8) eiects the drive of the flanged disc 5 which is keyed on the lay-shaft 6. A worm-wheel 7 and a worm 8 are keyed on the lay-shaft 6. I1`he worm-wheel 7 drives the spindle 9 of the centrifuge. The worm 8 keyed on the lay-shaft 6 drives the worm-wheel 10 (Figures 1 and 2) which is integral with a hub 11. The worm-wheel 10 together with the hub 11 is loose on the control shaft 15. The cam member 12 is provided with five cams of unequal height, as shown in Figures 1 and 3l. This cam member embraces the hub 11 of the worm-wheel 10 and is caused to rotate therewith by being keyed 2) are keyed to the control shaft 15. `trol shaft 15 is journaled in the two bearings 16 thereto. The cam member is however, displaceable on the hub 11. A driver attachment 13 is keyed to the hub 1l of the worm-wheel 10. The eccentric 14 (Figure 1) and the cam 38 (Figure The conand 17. The worm-wheel together with its hub 11 is loose on the control shaft 15. As, however, the worm-wheel 10 is in constant engagement with the worm 8 and the worm-wheel 7 with the spindle 9 of the centrifuge, as soon as the centrifuge is set in operation the spindle of the centrifuge together with drum, the wormwheel 1i) with its hub 11, the driver 13 and the cam member 12 are set in motion. The cam member 12 as well as the driver 18 will thus rotate whereas the control shaft 15 together with eccentric 14 and cam 38 remain stationary in the rst instance. The lay-shaft 6 rotates in practice at 800 revolutions per minute and as the transmission ratio from the worm-wheel 7 to the spindle 9 of the centrifuge is 1:5, the spindle of the centrifuge together with the drum will rotate at L1000 revolutions per minute. The worm 8 keyed on the lay-shaft 6 is single-threaded; in practice the worm-wheel 10 has 180 teeth so that the number of revolutions per minute executed by this worm-wheel and the cam-member 12 together with the driver 13 is equal to 2300+100, i. e., amounts to 8 revolutions per minute.

18 (Figure 3) is a control wheel loose on the shaft 36. The spring 19 exerts a braking effect on the control wheel 18 so that the latter shall not rotate too freely on the shaft 36. 20 is a catch or detent. 21 is a spring pressing the catch or detent outwardly. The levers 27, 28, 29 are integral and are free to move about the shaft 36, Figures 3. The lever 28 carries the control pawl 3l. A ball-bearing 22 is carried at the end of the lever 27. The spring 30 acts on the integral levers 27, 28, 29 so as to cause the ball-bearing 22 always to Contact with the cam member 12. On each rotation of the cam member 12 one of its cams will depress the lever 27 and according to the height of the corresponding cam (there are five cams) will cause the control-wheel 18 to be turned through an extent equivalent to one, two, three, four or five teeth. Now asthe controlwheel 18 is provided with 200 teeth, the wormwheel 10 or the cam member 12 together with the driver 13 must make two hundred revolutions in order that the control-wheel may make one revolution. As already pointed out, the wormwheel 10 executes 8 revolutions per minute, so that the control-wheel 18 will make one revolution in every 200-:-8=25 minutes. In the case when the 'control-wheel is advanced by two teeth, it makes one revolution in every 12.5,minutes, three teeth-every 8.35 minutes, four teeth-every 6.25 minutes. five teeth-every 5 minutes. binations are obviously possible. All that is necessary is to choose the height of the cams on the cam member 12 correspondingly if it is desired to advance the control-wheel by more than five Other comteeth per rotation, or else to provide the controli by engagement of its projections 25 upon the prol jection 24 and consequently its projection 67 can be gripped bythe arriving trigger 20. Figure 7 shows a section through the device in this condition.

In Figure 8, the control wheel lihas turned l further and thereby brought the pawl with its projection 68 into the vicinity of the projection 70 of the drive element 13. However, inasmuch as the drive element 13 turns continuously it carries along the pawl and thereby the eccentric element 14 is secured to the pawl.

The pawl 32 prevents a retrograde motion of the control-wheel 18 at the instant at which the lever 27 leaves the cam. The pawl member or an, chor 26, Figures 1 and 2 is carried by theeccentric 14 and is free to move about the pivot 37. It has two projections 67 and 68. The pawl 26 is constantly urged outwardly by the spring `23. As soon as the detent 20 secured on the control-wheel 18 comes into the vicinity of the projection 67 of the pawl 26 it engages therewith causing the pawl 26 to slide downwardly off the bolt 24. As the spring 23 urges the pawl 26 outwardly, the pawl on the side opposite to the spring will be urged inwardly and contact with the positively driven continuously rotating driver 13 until a hub on the latter engages with the projection .68 of the pawl 26 and drives the pawl 26. Now as the pawl 26 is secured to vthe eccentric 14 by bolts 37, and also as the eccentric is keyed on the control-shaft 15, the eccentric together with pawl 26 and control-shaft 15 is set in motion, or connected to the worm-wheel 10 and its hub 11 and rotates until the projection 25 on the pawl 26 again arrives at the bolt 24 which again urges the pawl 26 inwardly and in consequence releases the engagement between co-operating projections on pawl and driver 13. In order that the projection o n the pawl 26 shall not engage with the bolt 24, these two projections 67 and 68 are relatively displaced, as shown in Figure 3.

As already mentioned, the eccentric 14 is keyed to the control-shaft 15. The drum control cam 38, Figures 2 and 3, is also keyed to the controlshaft 15. The front portion of the eccentric 14 i is provided with a flat portion 39 on which runs the pulley 69 of the feed-control lever 33, Figure 2, during the working period the drum control cams 38, Figures 1 and 3, actuate and depress the lever 40, thus depressing the drum control rod 41, Figure 1, whereas after the operation of these cams the control rod 41 is returned to its rest position by means of a spring 42 (Figure 1).

lThe cam member 12 is moved to-and-fro by means of a change lever 43, Figures 1 and 2 This lever is keyed to the shaft 45, Figures 1 and 2, together with the external lever 44. The five stops 46 permit of an exact setting of the ve cams of the cam member 12, even during running.

In initiating the operation of the centrifuge, the speed of rotation of the drum is first brought to its full value and the valve 47 is then opened. The liquid to be clarified passes in through 48, past the circular valve 49 and the feed socket 50 in the direction indicated by the arrow into the hollow space 51, whence it passes into the interior of the drum by way of a pluralty of apertures 52, Figures 1 and 5. The liquid passes through the drum in the direction of the arrows. During its flow the liquid is freed from all specifically heavier foreign bodies by the action of the high centrifugal force, these foreign bodies being deposited on the oblique or inclined walls of the drum. The clarified liquid leaves the drum at 53 and passes into the receiver 5.4 from which it discharges by way of the socket connections Fig. ures 1 and 2.

By means of the lever 43 a higher or lower cam is introduced under the lever 27 and ball-bearing l22, according to the sludge-content of the liquid te be clarified, but .in actual Vpractice the drum is permitted to run until it is .clogged or tiled with sludge. As already described, as soon as the detent 20 secured on the control-wheel 18 sets the pawl 26 in motion, the control-shaft 15 is rotated. During the periodic working of the centrifuge, the eccentric 14 closes the circular valve 49 by means of lever 33, plug-member 34 and rod attached thereto, and thus interrupts the supply. The drum control cam 38 then immediately actuates the lever 40 which depresses the drum control rod 41 together with the annulus 56 connected therewith, so that the valves 58 are operated and drawn inwardly by means of the tilting-lever 57, the upper lighter arm 73a of which is movable in a slot 73 of the valve 58 and through pressure upon the lug 72 actuates the valve 58. The sludge collected in the drum passes out through 59 Figures 1 and 5 and in consequence of the oblique surface of the receiver 60 into which it is discharged the sludge passes in the direction of the arrow to the outlet 61 whence the solid matter can be conveyed by means of a worm conveyer or the like.

As soon as the drum control cam 38 runs off the roller of the lever 40, the spring 42 forces the drum control rod 41 together with annular member 56 upwardly, and under the action of centrifugal force the valves 58 again close the discharge apertures of the drum. The lever 33 then passes from the circular part of the cam 14 to the fiat part thereof, assumes the position shown in Figure 2 and returns the circular valve to the setting shown in Figure 1 so that the supply pipe is again opened and the operation re-commences.

The drum of the centrifuge consistsof an upper half 62 and a lower half 63 which are secured together by means of a number of screws 64 and form a unitary whole with the spindle 65. The

apertures provided along the line of greatest circumference of the drum for discharge purposes, see Figures 4 and 5, extend around the entire circumference of the drum and are only interrupted by the sections through which pass the bolts holding the two halves of the drum together.

A resilient packing material may be provided at the outer ends of the slides 58 to assist in obtaining a hermetic sealing of the drum. The

slides 58, together with the control rod 41 with i its annular member 56 and the tilting levers 57 rotate at the same speed as the centrifuge drum. Due to the high centrifugal forces of their masses the slides 58 are pressed against the wall of the drum or closure surfaces with great pressure, so

and this ensures a continuously smooth running of the drum even at the highest speeds. The slides 5B are made from a light metal such as aluminium or its alloys and are exactly the same weight, and notwithstanding its small specific gravity this light metal is sufficiently strong to prevent the slides from breaking when opened.

In spite of the slides being made from light metal their centrifugal force is nevertheless so great that very large forces would be required to operate them if they were not balanced.

The centrifugal force is calculated from the formula ot C (in kg.)=

in metres per sec. 91:9.81 and ris the radius of rotation in metres of G. If the-weight 'of the slide is 22@ grams, the radius of rotation of the centre of gravity of a slide 6.16 metres, the speed of rotation of the drum 400G revolutions per minute, then the centrifugal force acting on one slide is Vderived as follows:-

V: 2 XIIX 0. 16 X 67 metres/sec.

@-220 l ganse-922e 0 4489 9 81 0 16- 0.16 628.46 kg.

This figure shows the high centrifugal forces which have to be taken into consideration. The levers 57 are made of steel and are free to pivot about the pins 66. rIhe lower part of the levers 57 is heavier than the upper` part and the relative weights of lower and upper parts, on which latter the slides are, it were, carried are such that if for example in our case where the calculation shows the centrifugal force acting on one slide to be 828 kg. the centrifugal force acting on the lower part of the lever 5? amounts to approximately 500 kg. so that the actual pressure closing the slide 58 amounts to 628 less 560 i. e. 128 kg. The pressure closing the slides 58 can, of course, be arbitrarily selected by increasing or reducing the weight of the lower part of the tilting lever. Thus the entire centrifugal force acting on the slides does not have to be overcome when the slides are moved inwardly to open the valves, but only the difference between the centrifugal force acting on the lower part of the tilting lever 57 and that actin#T on the upper part of the lever 57 together with the slide 58.

In consequence the requisite power of the control mechanism for discharging the drum amounts to only a fraction of that which would be required in the absence of this balancing. As all the slides are of the same shape and have exactly the same weight, and the entire aggregate of tilting levers and slides is exactly symmetrical, the equilibrium of the drum is not disturbed by opening the valves i. e. by moving the slides inwardly and the lower part of the tilting lever outwardly. If in spite of this due to an erroneous weight, a small disturbance should occur, this disturbance will be reduced to the least possible value because of the small specific gravity of the material from which the slides are constructed and the balancing of tilting lever and slides, but,

the calculation shows how great is the effect of the factor in (weight) and the eifect of balancing tilting levers and slides. Y

What I claim and desire to secure by Letters Patent is:-

1. In a high speed centrifuge, drum, sludge discharge and liquid intake control members, a main driving shaft adapted simultaneously to drive the drum and the sludge discharge and the liquid intake control members, a worm-wheel on said shaft, a drum spindle, gears cooperating therewith, said worma-wheel engaging with the gears of the drum spindle, and .a worm and worm-wheel continuously in engagement with each other for operating the control members.

2. In a high speed centrifuge, a main driving shaft, a control shaft disposed at right angles to the said main driving shaft, a worm-wheeland a hub firmly fixed together and loosely disposed on the control shaft, a driving attachment keyed to the said hub, a cam member axially displaceable on the said hub, a keyV between the hub and the cam member adapted to prevent rotation of the cam member on the hub, a plurality of diierently formed cams on the cam member and means controlled by said cams adapted to cause the sludge to discharge at various time intervals, means positioned by stops for displacing the cam member on the hub at will, said means consisting of levers A,mounted on a shaft at right angles to the cam member, a shaft arranged parallel to the cam member, a spring controlled angle lever rotatable on the last-named shaft, a roller on one arm of said angle lever to engage with the said cam member, and a control pawl on another arm of the said angle lever, the control pawl engaging with the teeth of a control wheel mounted coaxially with the said pawl carrying lever.

3. In a high speed centrifuge, a centrifuge drum, a main driving shaft for said drum having a control rod extending into an axial bore thereof, a control shaft disposed at right angles to the said main shaft, a cam and an eccentric rmly fixed to the said control shaft, a pull-lever connected to the control rod, a lever for regulating the supply of liquid to the drum of the machine and having a roller engaging the said cam, means for causing the control shaft to rotate once at regular intervals determined by the setting of an axially displaceable multiple cam member, said means consisting of a spindle on the said eccentric, a spring actuated pawl rotatable on the said spindle, a releasing projection on said pawl, a gripping projection and an engaging projection on said pawl and a stop disposed on the stationary part of the machine outside the track of the gripping projection of the pawl to co-operate with said releasing projection.

4. In a high speed centrifuge, a main driving shaft having a control rod extending into an axial bore thereof, a control shaft disposed at right angles to the said main shaft, a worm fixed to the main shaft, a worm-wheel xed to the control shaft, an eccentric xed to the control shaft, a lever for regulating the supply of liquid to the drum of the machine, a roller connected to the said lever,l the said eccentric being adaptedrto remove the roller and the lever in order to `regulate the supply to the drum, a cam fixed to the said control shaft, and a pull-lever connected to the control rod, the cam being adapted to remove the pull-lever in order to engage the control rod.

5. In a high speed centrifuge, a drum having openings therein, a drum spindle having two axial bores separated by a separating wall, one of the bores being provided adjacent the bottom of the drum, the other bore being in communication with the drum by means of openings for the purpose of leading fluid to the bottom of the drum, a movable control rod provided in the first-named bore, an annular driving member connected with the control rod, means connecting the driving member with the control rod and provided through the openings in the spindle for the purpose of holding the driving member slidably on the outer surface of the spindle surface, and a lever cooperating with vthe control rod to pull the rod downwardly.

KARL EGG.

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