| United States Patent | 3,899,128 |
| Joyce | August 12, 1975 |
Zonal centrifuge rotors
Abstract
Zonal centrifuge rotors are disclosed which have a core that cannot be passed into the chamber of the bowl through an axial port in its top wall that is preferably an integral part of a bowl. Each core includes a hub and fins having detachably engaged portions and dimensioned to pass through the port when their portions are disengaged, for core removal, by first withdrawing the hub and, for core replacement, by inserting the hub with fins in predetermined positions in the chamber.
| Inventors: | Joyce; John E. (Weymouth, MA) |
| Assignee: |
International Equipment Company
(Needham Heights,
MA)
|
| Appl. No.: | 05/022,358 |
| Filed: | March 24, 1970 |
| Current U.S. Class: | 494/67 ; 494/38 |
| Current International Class: | B04B 1/00 (20060101); B04B 7/00 (20060101); B04B 7/08 (20060101); B04B 1/04 (20060101); B04b 001/04 (); B04b 005/04 () |
| Field of Search: | 233/30,32,33,42,27,28,16,44 |
| 362449 | May 1887 | Koelkebeck |
| 496120 | April 1893 | Hart |
| 825721 | July 1906 | Hartmann |
| 1643441 | September 1927 | Blanchard |
| 3047216 | July 1962 | Dolza |
| 3168474 | February 1965 | Stallman et al. |
| 3195809 | July 1965 | Pickels et al. |
| 3350002 | October 1967 | Pickels |
The present invention relates to zonal centrifuge rotors, and particularly to such rotors that, for their size and weight, are adapted to be rotated at substantially higher speeds than presently available zonal rotors of approximately the same size and weight. The present application is a continuation-inpart of my co-pending application Ser. No. 755,003, filed Aug. 23, 1968 and now abandoned.
In centrifuges, one of the factors limiting speeds is the strength of the rotor being used. Where rotor strength is achieved with a weight increase, the added weight becomes a limiting factor. The problem of rotor strength is particularly troublesome in the zonal field as zonal rotors have covers closing the bowl and include removable cores dividing the bowl into compartments into which and from which liquids are delivered and removed through axial distributing means.
Because of the necessity of zonal rotors having detachable covers to permit core insertions and removals, zonal rotors have not had sufficient strength to avoid undesirable speed limitations. The primary objective of the present invention is to provide zonal centrifuge rotors constructions that are free of these speed-limiting features.
In accordance with the invention this general objective is attained by providing a zonal centrifuge rotor including a bowl having a chamber in which the core is located and an axial port in its top wall in communication therewith, with the top wall being preferably an integral part of the bowl. The removable core consists of an axial hub and fins including detachably engaged portions providing an operative fin position in which the chamber is divided into compartments. The assembled core cannot be passed through the port when the portions are engaged but the hub and fins are dimensioned to pass therethrough when the portions are disengaged. Such disengagement is effected to permit core removal by withdrawing the hub and, in the case of core replacement, reengagement is effected by inserting the hub through the port with the fins in predetermined positions in the chamber.
Because the strength of a rotor bowl increases as the diameter of its opening decreases and because the invention also provides cores each of which may be so disassembled as to permit its hub to be removed from the bowl chamber through the port before the fins and reassembled within the chamber by reverse procedure, zonal centrifuge rotors are provided that are well adapted for use at substantially higher speeds than has hitherto been possible.
Another objective of the invention is to provide cores in each of which the interengageable portions of the hub and fins include cam parts operable to force the fins into their operative positions during the entry of the hub into the chamber.
Yet another objective is to provide a core construction in which the interengageable portions of the hubs and fins are vertical channels in the core dimensioned to slidably receive the inner edges of the fins, preferably with at least part of each channel and each inner edge being inclined to provide cam surfaces, and preferably with the fins becoming completely separated from the hub as the hub is removed from the chamber.
Another objective of the invention is to provide the bowls with means positively establishing the predetermined positions of fins that are detached from their hubs.
Yet another objective of the invention is to provide the cores with fin constructions including sectioned fins and special shapes to enable the port dimensions to be reduced to a satisfactory extent.
Where the fins have passages extending from their inner edges to their outer edges for communication with radial ports of hub passages when the core is assembled, the proximate ends of the passages open through the cam parts. Another objective is to ensure, where fins are vertically sectioned, a seal between the proximate ends of the sections of the fin passages in a like manner by providing the proximate edges of the fin sections with coacting cam parts through which such proximate passage ends open.
In the accompanying drawings, there is shown an illustrative embodiment of the invention from which these and other of the objectives, novel features, and advantages will be readily apparent.
I claim:
1. A zonal centrifuge rotor including a bowl having a chamber and an integral top wall having an axial port in communication with said chamber and of a diameter substantially smaller than that of the chamber, a cap for said port and detachably secured thereto, and a removable core within said chamber, said core and said bowl including portions detachably interengaged to ensure they rotate together, said core including an axial first part in the form of a hub and a plurality of second parts, each in the form of a fin having upper, lower, inner and outer edges, said inner edges extending into the space directly below the port and at least a part of the other edges abut the inner surfaces of the bowl to establish compartments, means in the bottom of said chamber receiving and slidably holding each second part in a predetermined radial position, said hub and fins including detachably engaged sets of connecting portions disengageable by upward movement of the hub relative to the fins, said hub and each of said fins dimensioned for passage through said port, said connecting portions renegageable on downward movement of the hub with the fins in said radial position.
2. The zonal rotor of claim 1 in which the detachably engaged connecting portions include means operable to effect radial movement of the fins into their compartment-establishing positions as the hub is inserted into its core-establishing position within the chamber.
3. The zonal rotor of claim 1 in which each of the lengthwise portions of the hub are channels and the lengthwise portion of each fin is in its rear edge and the channels and the rear fin edges are inclined downwardly and inwardly inclined cam parts that coact on the assembly of the core within the chamber to effect the compartment-establishing fin positions.
4. The zonal rotor of claim 3 in which the hub has a passage opening radially through the cam part of each channel and each fin has a passage opening at one end through the cam part of its rear edge and at the other end through its front edge, the proximate ends of the passages being in communication when the fins are in their compartment-establishing positions.
5. The zonal rotor of claim 1 in which the portion of the bowl that is engaged by a portion of the core to ensure their rotation together is an axial boss on the bottom of the bowl, there are radial channels in the boss, the hub has a recess receiving the boss, each fin includes an inwardly disposed portion adjacent the bottom of its inner edge extending under the hub and into one of the channels of the boss to slidably support that fin, the detachably engaged portions include coacting cam parts disposed, when slidably engaged, to effect radial movement of the fins into their compartment-establishing positions.
6. The zonal rotor of claim 1 in which the bowl includes an axial boss in the chamber, the fin holding means are radial outwardly opening channels in the boss with their closed ends close to the bowl axis, the upper edge of each fin has a notch increasing in depth towards the inner end thereof, and the outer ends of the upper and lower edges having a rounded mergence with the outer edge which are in engagement with corresponding portions of the inner surface of the bowl and which, with the notch, enable the inner part of each fin to be raised to clear the radial channel by which it is held and then withdrawn from the chamber.
7. The zonal rotor of claim 1 in which each fin includes inner and outer sections and means whose proximate edges abut and include lengthwise tongue and groove portions slidably joining the fin sections together to enable them to be interconnected or separated while within the chamber.
8. The zonal rotor of claim 4 in which each fin includes inner and outer sections whose proximate edges include tongue and groove portions and intermediate coacting cam parts through which the fin passages open.
9. A core for a zonal centrifuge rotor bowl having a top wall overlying the core-receiving chamber and provided with an axial port, the core comprising a hub and fins, said hub and fins including detachably engaged sets of connecting portions disengageable by upward movement of the hub relative to the fins and reengageable on downward movement of the hub with the fins in predetermined positions within the bowl, said hub including one set of said connecting portions and each of said fins including an appropriate one of said other set of connecting portions, the detachably engaged portions enabling the fins to move radially outwardly relative to the hub and both sets of connecting portions including parts that become engaged on such movement of the hub, said parts of at least one set being cam parts disposed then to effect such outward movement of the fins.
10. The core of claim 9 in which each fin has top, bottom, inner and outer edges and the connecting portions of the hub channels and the connecting portions of the fins are their rear edges, and the parts that become engaged on downward movement of the core are both cam parts, each of the cam parts of the hub is an intermediate upwardly and outwardly inclined portion of each channel and the cam part of each find is an intermediate and correspondingly inclined portion of the rear edge thereof.
11. The core of claim 9 in which each fin includes inner and outer sections whose proximate edges abut and which include lengthwise tongue and groove portions.
12. The core of claim 10 in which the hub has passages opening radially through each cam part and each fin has a passage opening at one end through its cam part and at the other end through its outer edge, and in operational alignment with the appropriate radial opening on downward movement of the hub relative to the fins to a predetermined extent.
13. The core of claim 12 in which each fin includes inner and outer sections whose proximate edges abut and include lengthwise tongue and groove portions and intermediate cam parts through which the fin passages open.
14. A fin for a zonal rotor core having a hub provided with vertical, fin-receiving open-ended slots the lower portions of which are inwardly and downwardly inclined cam surfaces and radial ports opening through its cam surfaces, said fin having upper, lower, inner and outer edges, said inner edge dimensioned to fit a hub channel and the lower portion thereof and being downwardly inclined to define a cam, said fin also having a passage effecting communication between the cam of its inner edge and the central portion of its outer edge.
15. The fin of claim 14 in which the upper edge has a notch increasing in depth towards its inner edge and the outer end of the upper and lower edges have a rounded mergence with the outer edge.
16. The fin of claim 15, the fin including inner and outer sections, the proximate edges including lengthwise slidably engageable tongue and groove portions.
In the drawings:
FIG. 1 is a vertical section of a zonal centrifuge rotor in accordance with the invention;
FIG. 2 is a section taken approximately along the indicated lines 2--2 of FIG. 1;
FIG. 3 is a fragmentary, perspective view of the core engaging portion at the bottom of the bowl;
FIG. 4 is a top view of the hub of the core;
FIG. 5 is a perspective view, on a reduced scale, of a fin in accordance with another embodiment of the invention;
FIG. 6 is a fragmentary bottom view of the bowl showing the means by which it is secured to the drive spindle of a centrifuge; and
FIG. 7 is a fragmentary vertical section, on an increased scale, of the threaded connection between the port and the cap therefor.
In the embodiment of the invention illustrated by the drawings, the bowl of a zonal centrifuge rotor is indicated at 10 and includes an integral top wall 11 having a central boss through which the port 12 extends and which defines an upwardly disposed rim 13. The port 12 opens downwardly into the chamber 14 in axial alignment with a centering boss 15 having a diametrically disposed rib or key 16 and a series of radial slots 17. The bottom of the bowl 10 has a boss 18 for connection with the drive of the centrifuge.
The rim 13 has an annular groove for the sealing ring 19 and the port 12 has threads 20 adjacent its upper end. A cap, generally indicated at 21, includes an axial cylindrical portion 22 provided with threads 23 adjacent its upper end for locking engagement with the threads 20. As will be noted from FIG. 7 the threads 20 and 23 have contact surfaces only in horizontal planes. The cap 21 is also provided with an annular groove 24 in the undersurface of its marginal flange 25 receiving within it the rim 13 when the cap 21 is secured. It is preferred that the top wall have an annular channel 11A to effect an increase in the axial extent of the rim 13 to enable the overlap of the cap 21 relative thereto to be correspondingly increased. The cap 21 also includes an axial bore 26 having a counterbore 27 in its outer or upper surface.
The centrifuge core consists of a hub, generally indicated at 28, having angularly disposed flat sides 29 which are shown as upwardly and inwardly inclined and as terminating in a shoulder 30 above which there is a cylindrical, axial neck 31. In the bottom of the hub 28, there is an axial recess 32 dimensioned to receive the centering boss 15 and provided with a transverse slot or keyway 33 providing a positive hub-to-bowl connection when the key 16 is entrant thereof.
The height of the hub 28 is equal to the bowl depth and its neck 31 is dimensioned to extend through the bore 26. The neck 31 has vertically spaced grooves for sealing rings 34 and in its upper end, there is a socket 35 with a central boss having an axial bore 36 extending through the neck 31 and it includes radial ports 37, one for each flat side 29 and extending across the upper surface of the shoulder 30. Vertical bores 38 extend downwardly through the neck and hub and each has a radial outlet 39 in the appropriate one of the channels 40 extending vertically along the junction between adjacent sides 29 of the hub 28.
The lower sealing ring 34 is a seal for the bore 26 while the upper sealing ring 34 is entrant of an annular detent groove 41 in a generally indicated cap 42, the cap 42 having relief ports 43 opening into the groove 41. A manually engageable knob 44 is connected to the cap 42 by a ball bearing unit 45 thereby enabling the cap 42 to be gripped and pulled from the neck 31 while the centrifuge is in operation.
Fins 46, when attached to the hub 28 within the bowl chamber 14, divide the chamber 14 into compartments 47, see FIG. 2. Each fin 46 has its inner edge dimensioned to slidably fit a hub channel 40 and with its bottom part entrant of and held by a slot 17 in the boss 15. The inner fin edges and the channels 40 are complemental in shape with each inner fin edge having an intermediate outwardly and upwardly inclined surface defining a cam part 48 through which one end of a passage 49 opens with the other end opening through a nipple 50 in its outer edge into a groove 51 which is of maximum depth when it extends between the compartments 47 and which more or less vanishes in each compartment as shown in FIG. 2. The inner edge of each fin 46, below its cam part 48, tapers downwardly and inwardly as at 52. Each cam part 48 is engageable with a like intermediate cam part 53 with which each hub channel 40 is provided and through which a radial outlet 39 opens.
With a core in accordance with the invention, each fin 46 may be positioned in the chamber 14 in a slot 17 thereby to be held upright in a predetermined position. The hub 28 may then be inserted through the port 12 with the inner edges of the fins 46 entering the hub channels 40. As the hub 28 is bottomed, the cam parts 48 and 53 coact to force the fins 46 outwardly into their operative, compartment defining relationship with the engaged cam parts providing a tight seal at the junction of the outlets 39 and the passages 49. If desired, each fin cam part 48 may have an annular recess surrounding the inner end of its passage for a sealing ring 54, see FIG. 5. When the core is to be removed, the cap 21 is first detached and the hub 28 is then lifted free with the fins 46 becoming detached so that each may subsequently be removed.
It will be noted that each fin 46 is shown as having a notch 55 in its upper edge which increases in depth towards the inner end thereof and that the upper and lower ends of the outer edge of the fins are rounded to conform to the curvature at the top and bottom of the chamber 14 and that between their rounded ends, the outer edges are shown as straight. When a fin 46 is to be removed the notch 55 permits the rear of that fin to be raised to clear the boss 15 so that it then may be removed through the port 12.
Where further reduction in the diameter of the rotor port relative to the diameter of the bowl chamber is wanted, the fins may be made in sections as is illustrated in FIG. 5. The fin shown in FIG. 5 is similar to that previously described with the reference numerals for the corresponding parts being distinguished by the suffix addition A. The fin 46A includes vertically divided inner and outer sections 56 and 57 whose proximate edges abut and include a tongue and groove portions 56A and 57A, respectively, and intermediate cam parts 58 and 59 through which the proximate ends of the passage 49A open and by which they are sealed together when the fins 46A are operatively positioned within the rotor.
It has been noted that where the rotor bowl has an integral top wall, the rotor strength increases as the diameter of its axial port 12 decreases. No substantial advantage results if the port diameter is much in excess of 55% of the inside diameter of the bowl and the construction and assembly of the core becomes a problem if the diameter of the port 12 is much less than 25% of said inside diameter. By way of example, a rotor whose port 12 was 51.6% of the inside diameter of the chamber and having a capacity of 7.5% greater than that of a comparable rotor is capable of operating at a 16.5% higher speed than the rotor of standard configuration thus affording a 36% increase in centrifuge force and an increase of 46% in operating efficiency.
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