US2991887A

US2991887A - Vibratory centrifuge

Info

Publication number: US2991887A
Application number: US702404A
Authority: US
Inventors: Wirth Thomas; Kocher Walter
Original assignee: Individual
Current assignee: Individual
Priority date: 1956-12-19
Filing date: 1957-12-12
Publication date: 1961-07-11
Anticipated expiration: 1978-07-11
Also published as: DE1043958B; NL107065C; FR1195326A; CH360028A

Description

July 11, 1961 T. WIRTH ETAL 2,991,887

. VIBRATORY CENTRIFUGE Filed Dec. 12, 1957 3 Sheets-Sheet 1 INVENTORS. mamas Il {r513 I BY Wz/zer fioaer W n w July 11, 1961 T. WIRTH ETAL 2,991,887

VIBRATORY CENTRIFUGE Filed Dec. 12, 1957 3 Sheets-Sheet 2 711/ III/1n 6 $0 INVENTORSn Tfiozzzas Mhf/Z July 11, 1961 T. WIRTH ET AL 2,991,887

VIBRATORY CENTRIFUGE Filed Dec. 12, 1957 3 Sheets-Sheet 3 United States Patent Office Patented July 11, 1961 Obermenzing, Germany Filed Dec. 12, 1957, Ser. No. 702,404

Claims priority, application Germany Dec. 19, 1956 8 Claims. (Cl. 210-376) This invention relates to a vibratory centrifuge of the kind having a basket which is rotatably mounted in a centrifuge housing and is reciprocated in the direction of its axis of rotation for the purpose of effecting the discharge of the centrifuged solids therefrom.

In known centrifuges of this type, the rotated basket increases in diameter in the direction toward the discharge end thereof, and the perforated wall of the basket is inclined relative to the axis of rotation at an angle corresponding approximately to the angle of repose of the material which is to be centrifuged. In order to effect the discharge of the centrifuged solids from the basket, the latter is reciprocated, by an eccentric, cam or the like acting upon the basket shaft which is mounted for axial sliding. The purpose of such an arrangement is to provide for the discharge of the centrifuged solids with the least possible damage to the granular structure thereof and to the perforated wall of the basket because only the component of the centrifical force which is perpendicular to the basket wall acts to urge the centrifuged solids against the wall. In order to assure discharge of the centrifuged solids, even under conditions of varying viscosity, the component of the centrifical force which acts in the axial direction of discharge is reenforced by the parallel component of the impulse resulting from reciprocation of the basket. However, it has been found that 'the rate of discharge cannot be satisfactorily adjusted with respect to the properties of the centrifuged material, even when provision is made for varying the amplitude and frequency of the reciprocation of the basket. Thus, the time of dwell of the centrifuged material in the basket is too short for satisfactory dewatering of the centrifuged material when a material of high fluidity is centrifuged, and supplementary dewatering is then required. On the other hand, when centrifuging highly viscous materials, the time required for the centrifuging operation is increased to an undesirable extent because of the unnecessarily long dwell time of the material in the centrifuge basket. These disadvantages may be overcome by maintaining a stock of centrifuge baskets having different opening sizes, which are interchanged, as required, for adaptation to the properties or characteristics of the material to be centrifuged. However, the initial cost of a vibratory centrifuge is substantially increased by such spare baskets, and centrifuging operations are slowed down by the time required for interchanging baskets.

Accordingly, it is an object of the present invention to provide an improved centrifuge of the described type which, by simple means, permits the achievement of the desired degree of dewatering of the centrifuged material independent of the properties of the latter.

In accordance with an aspect of the invention, the foregoing object is achieved by providing a centrifuge basket having an open end for, discharge of the centrifuged material therethrough and a wall which is cylindrical at least in a portion of the basket adjacent the opposite end of the latter, a pusher bottom which is mounted within the cylindrical portion of the basket for rotation with the latter, but independent of the axial reciprocation of the basket, so that, when the basket is reciprocated, a relative reciprocation occurs between the basket and the pusher bottom and the latter acts to progressively 2 displace the centrifuged material toward the open end of the basket.

In one embodiment of the invention, the pusherbottom is mounted on a shaft which extends axially into the basket through the open end of the latter, one end of the shaft being supported by a bearing assembly carried by the centrifuge housing to permit rotation of theshaft while preventing axial movement of the latter, while the other end of the shaft is coupled to the basket for rotation with the latter while permitting axial movement of the basket relative to the shaft so that the length of the stroke of the relative reciprocation of the basket and pusher bottom is equal to the length of the reciprocating stroke of the basket.

In a preferred embodiment of the invention, the pusher bottom and the basket are both axially reciprocated, but in opposite directions, so that the stroke of the relative reciprocation of the basket and pusher bottom is greater than the reciprocating stroke of the basket, thereby to increase the rate at which the pusher bottom can effect the axial discharge of centrifuged material from. the basket.

In still another embodiment of the invention, the pusher bottom is incorporated in a reciprocating centrifuge, for example, of the kind disclosed in U.S. Patent 2,872,045 to Thomas Wirth, Karl-Heinz Nebhuth and Karl Wenger, for Oscillating Centrifuge, wherein a balancing mass is mounted for reciprocation in the direction of the rotational axis of the basket and the basket and balancing mass are reciprocated in opposite directions and are elastically coupled to each other to form a dual-mass oscillating system, with the pusher bottom being rigidly connected to the balancing mass for recipro-v cation with the latter relative to the reciprocated basket.

Further, in accordance with an aspect of this invention, the centrifuge basket may be of stepped configuration increasing in diameter toward the open end thereof with the pusher bottom being installed within the portion of the basket having the smallest diameter, while pusher rings connected to the pusher bottom for reciprocation with the latter relative to the reciprocated basket, are disposed at each step or increase in diameter of the basket to provide successive impulses for moving the centrifuged material towards the open discharge end of the basket as such material moves along the basket wall. Such an arrangement is of particular advantage in connection with the dewatering or centrifuging of materials which are diflicult to filter, such as, for example, sugar products, citrates and the like, which might be compressed or compacted if subjected only to the action of the reciprocated pusher bottom disposed at the end of the basket remote from the open discharge end of the latter.

The above, and other objects, features and advantages of the invention, will be apparent in the following detailed description of illustrative embodiments thereof, which is to be read in connection with the accompanying drawings, forming a part hereof, and wherein:

FIG. 1 is an axial section-a1 view of a vibratory centrifuge embodying the present invention;

FIG. 2 is an axial sectional view of a vibratory centrifuge constructed in accordance with another embodiment of the invention;

FIG. 3 is an axial sectional view of a vibratory cent-rifuge constructed in accordance with still another embodiment of this invention;

FIG. 4 is an axial sectional view of a vibratory centrifuge constructed in accordance with still another embodiment of this invention; and 1 FIG. 5 is a view similar to that of FIG. 4, but showing still another embodiment of the invention. l

Referring to the-drawings in detail, and initially to FIG. 1 thereof, it will be seen that a vibratory centrifuge embodying the present invention includes a centrifuge basket 1 having a cylindrical perforated side wall 2 which is covered, at its inner surface by a screen liner 3. The basket 1 is open at one end for the discharge of the centrifuged material therethrough, and the other end of the centrifuge basket is closed by an end wall 15 having a central hub 16 which is fixedly secured on a basket shaft 17. The shaft 17 is axially slidable, as indicated by the arrows, within a sleeve 19, and the latter is rotatably supported in a bearing 20 carried by a transverse partition 21 of a centrifuge housing 4, so that the centrifuge basket 1 is free to rotate about its central axis and to reciprocate in the direction of that axis relative to the housing 4. A suitable conventional drive and reciprocation generator (not shown) is associated with the sleeve 19 and the shaft 17 in order to effect rotation of the basket 1 and axial reciprocation thereof.

The material to be centrifuged is supplied to the basket 1 through the open end of the latter by way of a feed pipe which is fixed relative to the housing 4 and extends downwardly and then axially into the open end of the basket. Within the basket 1, the end portion of feed pipe 5 is slidably received in a cylindrical extension 6 of a funnel 7 which fiairs outwardly and opens in the direction toward the end wall 15 of the basket.

In accordance with the present invention, a circular pusher bottom 8 having an outer diameter only slightly smaller than the inner diameter of the cylindrical wall 2 of the basket is disposed within the latter between the end wall 15 and the funnel 7. The pusher bottom 8 is centrally mounted on a shaft 9 which is aligned with the axis of the basket '1 and which passes axially through the funnel 7 and then through a stuffing box or seal 11 in the vent portion of feed pipe 5. The end of shaft 9 extending out of feed pipe 5 is supported by a bearing assembly carried by the housing 4 and including a thrust bearing 12 preventing axial movement of shaft 9 relative to housing 4 and a radial bearing 13 accepting the radial loads on the shaft 9. The opposite end of shaft 9 extends through pusher bottom 8 and is provided with an end portion 14 of square or other non-circular crosssection, which extends into the basket wall 15 and the hub 16 and is axially slidable in a recess 18 of corresponding square or other non-circular cross-section provided in the adjacent end of basket shaft 17. Thus, the cooperating end portion 14 of shaft 9 and recess 18 of shaft 17 provide an non-rotatable, but axially slidable coupling between the basket and the shaft 9, and hence also the pusher bottom 8.

As seen in FIG. 1, the funnel 7 is secured to the pusher bottom 8, for example, by means of straps 22, so that the periphery of the funnel 7 will be spaced axially from the face of pusher member 8 directed toward the open end of the basket, while the funnel 7 will participate in the rotary movement of pusher bottom 8 with basket 1.

During operation of the centrifuge described above with reference to FIG. 1, the basket 1 is rapidly reciprocated in the direction of its axis and simultaneously rotated about that axis by suitable actuation of the shaft 17 so that material to be centrifuged, upon entering through the feed pipe 5, is deposited by the feed funnel 7 against the peripheral portion of the surface of pusher bottom 8 facing toward the open end of the basket. Since the pusher bottom 8 is held against axial movement relative to the housing 4, while the basket 1 reciprocates with respect to the housing, it is apparent that relative axial reciprocation will occur between the basket and the pusher bottom. During the reciprocating stroke of the basket 1 in the axial direction away from the open discharge end thereof,

centrifuged material abutting against the peripheral portion of the pusher bottom will be pushed, by the latter, along the screen liner 3 in the direction toward the open discharge end of the basket. When the return reciprocating stroke of the basket occurs, that is, when the basket 1 moves in the axial direction toward the open discharge end thereof, an annular free space will be formed between the pusher bottom 8 and the layer of centrifuged solids previously advanced by the pusher bottom, so that additional material to be centrifuged can enter this annular free space from the feed funnel 7. Thus, as the basket 1 is axially reciprocated and the pusher bottom 8 is held against axial reciprocation, the latter will act to progressively feed the centrifuged solids toward the dischargeend of the basket.

Although the centrifuge illustrated in FIG. 1 has a side wall 2 which is cylindrical, that is, of equal diameter along its entire length, it will be understood that such cylindrical configuration of the side wall of the basket is necessary only in that portion of the latter accommodating the pusher bottom 8, and that the remainder of the basket extending from the vicinity of the pusher bottom to the open discharge end may be given a conical configuration so that the basket increases in diameter toward its open discharge end and a component of the centrifical force will be available to act upon the centrifuged solids in the direction along the conical wall surface, thereby to assist in the movement of the centrifuged solids toward the open discharge end.

Further, it will be apparent that, in the embodiment of the invention described above with reference to FIG. 1, the relative reciprocation of the pusher bottom 8 and basket 1 has a stroke equal to the reciprocating stroke of the basket 1. However, the pusher bottom may be also axially reciprocated relative to the centrifuge housing, but with the direction of the reciprocating movement of the pusher bottom being always opposed to the direction of reciprocating movement of the centrifuge basket, thereby to increase the length of the stroke of the relative reciprocation of the pusher bottom and basket for correspondingly increasing the rate at which the pusher bottom is effective to discharge centrifuged solids from the basket. Such an arrangement is illustrated in FIG. 2, wherein the centrifuge basket 1a is mounted on a shaft 17a which is carried by a bearing 20a in a partition 21a of the centrifuge housing 4a so that the centrifuge basket is free to be rotated about its central axis (by means not shown in the drawing) and also to be axially reciprocated by a conventional electromagnetic oscillator 23 connected to the shaft 17a. As in the centrifuge of FIG. 1, the centrifuge of FIG. 2 is provided with a circular pusher bottom 8a fitting closely within the basket 1a and carried by a shaft 9a having an end portion 14a of non-circular cross-section slidably received in a recess 18a having a mating cross-section and formed in the adjacent end of shaft 17a to open through the end wall 15a of the basket, so that the pusher bottom 8a is rotated with the basket and is independent of the axial reciprocation of the latter. As distinguished from the first described embodiment of the invention, in the centrifuge of FIG. 2, the end of the shaft 9a extending through the open end of the centrifuge basket is rotatably mounted in a bearing 13:: carried by the housing 4a, and such bearing 13a merely gives radial support to the shaft 911 which is free to reciprocate axially relative to the housing. Further, the end of shaft 9a extending out of housing 4a is equipped with an independent electromagnetic oscillator 24 which effects axial reciprocation of the shaft 9a and which, as diagrammatically illustrated in FIG. 2, is connected to the same source of electric current as the oscillator 23. The two

oscillators

23 and 24 are arranged so that the

corresponding shafts

17a and 9a are always moving in opposite directions. If the

oscillators

23 and 24 are of identical design, the reciprocating stroke of the pusher bottom 8a will be equal, in length, to the reciprocating stroke of the basket la, so that the length of the stroke of the relative reciprocation, which determines the rate at which the pusher bottom 8a effects discharge of the centrifuged solids from the basket 1a, will be twice that obtained with the arrangement of FIG. 1. r r r Although FIG. 2 does. not. illustrate any means for feeding material to be centrifuged into the basket 1a, it is to be understood that a feeding means similar to that described with reference to the embodiment of FIG. 1 may also be employed in connection with the embodiment of the invention illustrated in'FIG. 2.

Referring now to'FIG. 3, it will be seen that the vibratory. centrifuge there illustrated is of the kind operated-by a dual-mass oscillating system, for example, as disclosedin the afore-mentioned US. Patent 2,872,045 toThomas Wirth, Karl-Heinz Nebhuth and Karl Wenger. In the centrifuge of FIG. 3, the centrifuge basket 1b having a: cylindrical perforated side wall is once again mounted withv its axis extending horizontally within a centrifuge housing 4b. The shaft 17b having the basket 1b securely connected to one end thereof is hollow and is slidably received within, an elongated sleeve 26 which is rotatably supported, adjacent its opposite ends, by ball bearings 27 and 29 respectively carried by transverse walls or partitions'28 and .30 of the housing 4b. The end of the elongatedsleeve ,26 remote from the centrifuge basket projects from the housing 45 through the transverse wall 28 and carries a drive pulley 31 which is operatively connected with a pulley 33 by means of V-belts 32. The pulley 33 is mounted on the shaft of an electric motor 34 to be driven by the latter.

The elongated sleeve 26 has two elongated slots 35 and 36. which extend axially and are axially spaced apart at locations between the bearings 27 and 29. A collar 37 is slidably mounted on the sleeve 26 in the region of the slot 35, and the collar 37 is securely connected to the basketshaft 17b by means of a screw 38 which extends through the slot 35 and is free to move axially in the latter. The other slot 36 of the sleeve 26 registers with a slot 39 provided, in thehollow basket shaft 17, and a wedge or key member 40 passes slidably through the regis teririg slot 36 and opening 39 to connect a balancing mass member 41, which is slidable upon the sleeve 26, to a connecting rod 42 which is axially slidable within the hollow shaft 17b and which forms an axial extension of the shaft 9b carrying a pusher bottom 8b within the centrifuge basket 1b. Both the hollow basket shaft 17b and the connecting rod 42 project axially beyond the end of the sleeve 26 which carries the drive pulley 31 for connection to a hydraulic oscillator 43. The oscillator 43 includes a piston 45 which is connected to the end of the connecting rod 42 and is slidably arranged in a cylinder 44 connected tothe shaft 17b, The cylinder44 is, in turn, slidable within a guide housing 46 which has two pressure fluid supply lines 47 and 48 connected thereto and opening into annular channels or grooves 49 and 50 formed in the inner surface of the guide housing. Further, the cylinder 44 is provided with radial openings 49a and 50;: positioned .for, registration with the annular grooves 49 and50,respec'tively. The openings 49a and 50a communicate with the

interior spaces

51 and 52, respectiv'ely, within the cylinder 44 at theopposite sides of piston '45. The lines or conduits 47 and 48 are alternately connected to a source of fluid under pressure by a suitable valve arrangementv (not shown). Thus, when fluid under pressure is supplied tothe space 51 through the line 47, groove 49 and opening 49a, the piston 45, and hence the "connecting rod 42, shaft 9b, pusher bottom 8b, and balancing'mass member 4 1, are all displaced axially toward the left, as viewedin FIG. 3, while the cylinder, and hence, the shaft ;17b and the basket 1b, are all displaced toward theright, as viewed in FIG. 3. On the other hand, when fluid under pressure is supplied to the space 52 through the line or conduit 48, groove 50, and opening 50a, the piston 45, connecting rod 42, shaft 9b, pusher bottom 8b and balancing mass member 41 are displaced. axially toward the right, while cylinder 44, shaft 17b, and basket lb areall displaced axially toward the left. I

,1 Further, in theerrangement ofFIG. 3, thrust washers 53 and 54 aremounted onthe sleeve 26 against the .6011- fronting faces of ball bearings 27 and 29, respectively, and helical springs'55 and 56 extending around the sleeve 26 are axially interposed between the thrust washer-53 and the balancing mass member 41, and between thrust washer 54 and the collar 37, respectively. Finally, an additional helical spring 57, which extends around the sleeve 26, is axially interposed between the collar 37 and-the balancing mass member 41 to form a resilient coupling between the balancing mass member and the basketlb' carried by the shaft 17b to which the collar 37; is fixedly attached.

In the above described arrangement, theelastically or resiliently coupled basket 1b and balancing mass member 41 provide a dual-mass oscillating system, with the pusher bottom 8b which isconnected to the member 41 by way of the shaft 9b and the key 40, forming part of the balancing mass. With the mass of the basket 1b and, the balancing mass being properly adjusted relative to each other, a pressure impulse occurring in cylinder 44' causes simultaneous axial oscillations orfr eciprocations of the mass of the basket and of the balancing mass in opposite directions, and the springs 55 and 5 6 serve to' transmit opposed reactions to the reciprocations'to'the housing 4b,

so that neither the housing 4b nor the rotary drive, isinfluenced by, or subjected'to, the "axial vibrations of the centrifuge basket and of the bala'ncing'mass.

In the embodiment of FIG. 3, the pusher bot-tom 8b operates in the same manner as in'the embodiment described With reference to FIG. 2, but it is not connected to a separate .osci-llator. Since the pusher bottom 8b and the basket 1b always move in opposed directions relative to the housing 4b, it is apparent that the length of stroke of the reciprocation of the pusher bottom relative to the basket is twice the length of stroke of the'basket alone, thereby to provide a relatively high rate of discharge of the centrifuged solids.

Although each of the embodiments of the invention described with reference to FIGS. 1, 2 land 3, respectively, includes a pusher bottom adjacent the closed end of the centrifuge basket and reciprocated axially relativeto the latter to progressively. move the centrifuged solids toward the open end of the basket, by contact with the centrifuged solids only at a location adjacent the closed end of the basket, it is to be noted that, in accordance with this invention, arrangements may be provided within the basket for imparting additional impulses to the centrifuged solids as the latter move along the basket wall toward the open discharge end of-the basket. Thus, the present invention may be applied to centrifuge baskets of the kind which are enlarged stepwise towards the discharge end thereof, for example, as used in centrifuging materials, such as, sugar products, which are difficult to filtrate. Because of the great length of these baskets, the centrifuged material or solids is compressed while being fed toward the discharge end of the basket, so that the friction between the material and the basket wall is increased, and a single pusher bottom, as in the embodiments of FIGS. 1, 2. and 3, is no longer capable of providing adequate thrust for advancing the centrifuged material. Accordingly, referring to FIG. 4, it will be seen that, in the embodiment of the invention there illustrated, the centrifugebasket, generally identified at 10 has a side wall made up of perfo rated

cylindrical portions

58a, 58b, 58c and 58d of progressively increasing diameter.

The successive cylindrical sections or portionsof the side wall of the centrifuge have their adjacent ends disposed in axially overlapping relationship, while the ends of the

sections

58b, 58c and 58d facing toward the small diameter end .of the basket are provided with radially inward directed annular flanges 59a, 59b and 590, respectively, which connect to the sections 58a, 58b and 580, respectively, in order to define annular spaces 60a, 69b and 600, respectively, between theoverlapping end portions of the cylindrical wall sections, with such an- 7 nular spaces opening axially in the direction toward the relatively large diameter discharge end of the basket.

The'basket 1c has a pusher bottom 8c supported axially Within the portion of the basket defined by the wall section 58a of smallest diameter, while additional pusher rings 61a, 61b and 610 are slidably disposed in the annular spaces 60a, 60b and 600, respectively, and close the open ends of such spaces. Thus, in effect, each of the pusher rings forms an axially movable flange at the end of the

related section

58a, 58b or 58c which extends in the direction toward the open end of the basket.

The basket 10 is mounted on a hollow shaft 170 by way of an annular flange 65 extending from the latter and secured to rods or straps 66 whichextend axially from the wall section 58a of the basket. Further, the pusher bottom 8c is carried by a shaft 64 which is integral with a connecting rod 420, and a disc 63 is mountedon the shaft 64 between the pusher bottom 8c and the flange 65. The pusher rings 61a, 61b and 61c are connected to'the disc 63 by rods 62 so that the pusher rings will reciprocate axially with the pusher bottom 80 relative to the basket 10.

In the embodiment of FIG. 4, the hollow shaft 17c and the connecting rod 42c correspond to the hollow shaft 17b and the connecting. rod 42, respectively, of the embodiment of the invention previously described with reference to FIG. 3', and, a dual-mass oscillating system may be similarly provided for effecting axial reciproca tion of the basket 10 and of the pusher bottom 80 and the associated pusher rings in opposed directions.

As in the previously described embodiments, the material to be centrifuged is supplied to the basket 10 by way of a feed pipe 5c and a funnel 70 opening within the relatively small diameter end portion of the basket so that the material to be centrifuged is discharged against the pusher bottom 8c.- As in the embodiments of the invention described with reference to FIGS. 1, 2 and 3, the relative reciprocation of the pusher bottom 8c and of the basket 1c cause the pusher bottom to progressively propel 'the centrifuged solids along the wall section 58a in the direction toward the relatively large diameter open end of the basket. However, in the embodiment of FIG. 4, the pusher rings 61a, 61b and 61c, which reciprocate with the pusher bottom, provide additional impulses for moving the centrifuged solids toward the open end of the basket 1d includes frusto-conical, perforated

wall sections

58a, 58a and 58 with the adjacent ends of such sections being joined together by

structures

59d and 59e which define annular spaces 60d and 60e, respectively,

opening axially in the direction toward the relatively large discharge end of the basket and having cylindrical inner and outer surfaces. Pusher rings 61d and 61e are axially slidable within the annular spaces 60d and 60a, respectively, and are connected, by rods 62d, to the disc 63d.carried by the shaft 64d which supports the pusher bottom 8d within acylindrical extensiouat the small diameter end of the wall section 58d. As in-theembodiment'of the invention illustrated in FIG. 4, the basket 1d is secured to a flange 65d on the hollow shaft 17d by straps or rods 66d which extend 'slidably through suitable openings in the disc 63d, while the shaft 64d is integral with a connecting rod 42d, so thatthe connecting rod 42d and the hollow shaft 17d may be oppositely reciprocated, for example, by the dual-mass oscillating system of FIG. 3, in order to provide for the opposite reciprocation of the pusher bottom and pusher rings, on the one hand, and the basket 1d on'the other hand. Thus, when material to be centrifuged is supplied to the relatively small diameter end of the basket 1d by way of a feed pipe 5d and feeding funnel 7d, the reciprocated pusher bottom 8d causes initial movement of thecentrifuged solids along the wall section 58d. Thereafter, the reciprocated pusher rings 61d and 61e provide additional impulses for continuing the movement of the centrifuged solids along the successive wall sections 584; and 58 Since the

wall sections

58d, 58e and 58f are frusto-conical,. the 'centrifical forces acting upon centrifuged solids lying against such wall sections will have components acting along the wall sections in the direction toward the open discharge end of the centrifuge basket, thereby to assist or promote the movement of the centrifuged solids toward the open discharge end of the basket.

The above described embodiments of the invention all serve to ensure the controlled discharge of the centrifuged solids while avoiding damage to the granular structure of the latter. During the movement of the centrifuge basket in the axial direction opposed to the discharge movement of the solids deposited against the basket wall, such solids abut against either the pusher bottom alone, as in FIGS. 1, 2 and 3, or against the pusher bottom and the associated pusher rings, as in FIGS. 4 and 5, so that the deposited centrifuged solids are given a well defined impulse toward the discharge end of the basket. This permits the discharge of the centrifuged solids even from a cylindrical basket, as in FIGS. 1, 2 and 3, and improves the efliciency of the discharge movement in a basket having a frusto-conical wall, for example, as shown in FIG. 5. ..Fu.rther, the devices embodying the invention ensure uniform, practically continuous and adjustable movement of the centrifuged solids toward the discharge end of the basket, thereby to result in uniform dewatering of the material. The rate of movement of the centrifuged material through the basket, and therefore the capacity of the vibratory centrifuge embodying the invention can be increased, if necessary, to approximately twice the usual corresponding rates, by providing an oscillatory drive for the pusher bottom as well as for the basket, for example, as in the embodiments of FIGS. 2, 3, 4 and 5;

It should be understood that the basket of the centrifuge of our invention vibrates or oscillates at a relatively very high frequency. The frequency of the vibratory or oscillatory motions is approximately 1800 per minute, and the amplitude is about 10 to 1?. mm. As distinguished from such motions, pusher bottoms, so far as they have been already used in centrifuges, operate through a stroke of 35 to 65 mm. at strokes per minute. While these known pusher bottoms push centrifuged goods forcibly forward and out and largely destroy the granular structure of the material being centrifuged, any rubbing oflf by friction and loss of luster is eliminated when working with our vibratory centrifuge, which improves the quality of the centrifuged solids. In our centrifuge, the material is only shaken to cause the latter to slide along the basket walls. Our centrifuge is thus particularly suitable for the separation of crystalline materials, such as sugar, salt, and the like.

Although illustrative embodiments of the invention have been described in detail herein with reference to the drawings, it is to be understood that the invention is not limited to those precise embodiments, and that various changes and modifications may be effected therein without departing from the scope or spirit of the inven tion, except as defined in the appended claims.

What is claimed is:

1. In a vibratory centrifuge; the combination of a housing, a basket in said housing opening axially at one end for discharge of centrifuged solids through the latter and having a wall which is cylindrical at least in a portion of the basket adjacent the opposite end of the latter, means supporting said basket for rotation, a pusher bottom within said portion of the basket, means supporting said pusher bottom within the basket for rotation with the latter, and means effective to cause relative axial reciprocation of said pusher bottom and basket through a stroke having a minimum length equal to the length of the reciprocating stroke of said basket and a maximum length of approximately twice said length of the reciprocating stroke of the basket, with said means eifective to cause relative reciprocation, being also effective to axially reciprocate said basket at a frequency of the order of 1800 cycles per minute and through a stroke of approximately to 12 millimeters, so that, when material to be centrifuged is fed to said basket at the side of said pusher bottom facing toward said one end of the basket, the solids in the material collect on said Wall of the basket and are progressively displaced towards said one open end for discharge from the basket by said pusher bottom in response to the relative reciprocation of said basket and pusher bottom.

2. In a vibratory centrifuge; the combination as in claim 1, wherein said means efiective to cause relative axial reciprocation of said push-er bottom and basket includes means for axially reciprocating said basket and means for axially reciprocating said pusher bottom with the direction of axial movement of the latter being always opposed to the direction of axial movement of said basket.

3.In a vibratory centrifuge; the combination as in claim 1, further comprising means for axially reciprocating said basket, said means for axially reciprocating said basket including a balancing mass member reciprocable in the direction of the axis of said basket, means for reciprocating said balancing mass member in opposition to the reciprocation of said basket, and means elastically coupling said balancing mass member to said basket so that said basket and balancing mass member form a dualmass oscillating system, and wherein said means effective to cause relative reciprocation of said pusher bottom and basket includes rigid connecting means between said balancing mass member and said pusher bottom so that the latter reciprocates with said balancing mass member relative to said basket.

4. In a vibratory centrifuge; the combination as in claim 1, wherein said wall of the basket is cylindrical throughout the length of the latter.

5. In a vibratory centrifuge; the combination as in claim 1, wherein said wall of the basket further includes a frusto-conical portion extending from said cylindrical portion and increasing in diameter in the axial direction toward said one open" end of the basket so that a component of centrifugal forces acting on centrifuged solids collected on said wall exists along said frusto-conical portion to assist said pusher bottom in displacing the centrifuged solids toward said one open end.

6. In a vibratory centrifuge; the combination as in claim 1, wherein said wall of the basket increases in diameter from said cylindrical portion toward said one open end of the basket and further has at least one annular space opening axially toward said one end be tween inner and outer cylindrical surfaces at a location intermediate said cylindrical portion of the wall and said one end, and further comprising a pusher ring axially slidable in each annular space and means connecting said pusher ring to said pusher bottom for reciprocation with the latter relative to said basket, whereby each pusher ring further displaces the centrifuged solids along said wall toward said one open end of the basket in response to relative reciprocation of said basket and said pusher bottom and ring.

7. In a vibratory centrifuge; the combination as in claim 6, wherein said wall has at least one additional cylindrical portion with a diameter larger than that of the first mentioned cylindrical portion and extending from the latter in the direction toward said one open end, said first and additional cylindrical portions having axially overlapping end portions, and said annular space is defined between said axially overlapping end portions with said pusher ring forming a radial shoulder between said first cylindrical portion and said additional cylindrical portion.

8. In a vibratory centrifuge; the combination as in claim 6, wherein said wall has a frusto-conical portion extending from said cylindrical portion, and increasing in diameter, toward said one open end of the basket, and said annular space is located intermediate the opposite ends of said frusto-conical portion so that the displacement of the centrifuged solids along said frusto-conical portion of the Wall by said pusher bottom and pusher ring is further assisted by a component of the centrifugal forces.

References Cited in the file of this patent UNITED STATES PATENTS 2,685,370 Ruegg Aug. 3, 1954 2,755,934 Ruegg July 24, 1956 2,782,930 Heckmann Feb. 26, 1957 2,861,691 Linke et a1. Nov. 25, 1958