US 3770191 A
A compound articulated drive system for a centrifuge which prevents vibration of the centrifuge rotor during critical speeds of acceleration and de-celeration. Means are provided for automatically causing the center of gravity of the rotor to become aligned with the axial center of the drive system, maintaining that alignment, and eliminating vibration of the drive system and especially of the spinning rotor within critical ranges of speed during deceleration of the centrifuge. The foregoing is accomplished by the provision of a self-centering assembly comprising a separate rotor shaft pivotally articulated upon the centrifuge drive system shaft and by means of a captive slide block integrated with said assembly and movable on the drive shaft. During acceleration, the centering assembly automatically relocates itself and becomes aligned with respect to the dynamic axis of the rotor and remains fixed substantially in said dynamically aligned position throughout the centrifuging process and through deceleration until the rotor comes to a stop.
Claims available in
Description (OCR text may contain errors)
mte' States Patent 11 1 1111 3,770,191
Burn Nov. 6, 1973 MEANS FOR STABILIZING HIGH SPEED ROTORS  ABSTRACT  Inventor; J f Blum, Nm-walky Conn A compound articulated drive system for a centrifuge which prevents vibration of the centrifuge rotor during Asslgnee: Sorva" Newtown Conncritical speeds of acceleration and de-celeration.  Filed; June 28, 1971 Means are provided for automatically causing the center of gravity of the rotor to become aligned with the PP N05 157,174 axial center of the drive system, maintaining that alignment, and eliminating vibration of the drive system and 52 us. c1 233/23 A, 64/21, 74 573 especially of the Spinning rotor Within eritieal ranges of 51 1112.01 B04b 9/14 Speed during deceleration of the eehtrifuge- The fore-  Field of Search 74/573; 64/1 v, 21; going is aeeemplished y the provision of a self- 233/23 A, 23 210/368 68/233 centering assembly comprising a separate rotor shaft pivotally articulated upon the centrifuge drive system  References Cited shaft and by means of a captive slide block integrated UNITED STATES PATENTS with said assembly and movable on the drive shaft.
During acceleration, the centering assembly automatifi s Jr cally relocates itself and becomes aligned with respect 2:797:569 7 1957 K111)? III:IIIIIIIIIIIIII..... 68/233 to the dynamic axis ofthe rotor and remains fixed stantially in said dynamically aligned position throughout the centrifuging process and through deceleration until the rotor comes to a stop.
31 Claims, 7 Drawing Figures mgmguunv 61973 3.770.191
sum 1 or 3 II IIII I INVENTOR JOSEF BLUM- ATTORNEY 4 m 7 W 4 3 S U l 3 w F I 0 J A m 7 4i 5 4 7% a e 7 3 4| 7 \l\ 0 6 i .4 6 5/ 1 IQ:
SHEET 2 BF 3 PATENTED SW3 [7 4A. 2 Q E m A 7/, I i
ATTORNEY MEANS FOR STABILIZING HIGH SPEED ROTORS BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to certrifuges and more particularly to an improved centrifuge structure which prevents vibration of the centrifuge rotor and the rotor drive system during acceleration and deceleration thereof that might otherwise be caused by imbalance of the rotor or of the contents of the rotor, or both.
2. DESCRIPTION OF THE PRIOR ART Applicant is also the inventor of U. S. Pat. No. 2,827,229, issued March 18, 1958, which discloses a gyro-action centrifuge wherein the rotor and the rotor shaft housing are supported by means of resilient couplings. In that patent, the resilient mountings of the rotor, of the drive shaft, and of its housing, permitted the rotor to find and rotate about its own dynamic center without transmitting any appreciable vibration to the base assembly of the centrifuge. Furthermore, the flexible articulation of the rotor shaft and its housing permitted the upper end of the rotor shaft to move in an orbit to follow the path of the geometrical center of the rotor attached thereto. Notwithstanding the eminently satisfactory performance of the apparatus manufactured and sold under U. S. Pat. No. 2,827,229, nevertheless the present invention is believed to offer a superior solution to the problem of centrifuge rotor vibration and for accomplishing the prevention of vibration.
Further examples of prior art are disclosed in the references cited in the aforementioned U. S. Pat. No. 2,827,229. Reference may also be made to U. S. Pat. No. 2,249,292, issued to P. Kapitza, on July 15, 1941.
in the centrifuge system disclosed in U. S. Pat. No. 2,827,229, wherein resilient mountings are provided for the drive shaft, the drive shaft housing, and the rotor, the rotor describes a continuing gyroscopic action or orbiting movement of the rotor axis around the original vertical drive system axis. In this system, as well as in other centrifuge drive systems comprising rigid shafts and flexible shaft mounting means, there is the remaining problem of the possibility of vibration occurring during a critical range of speeds on acceleration and deceleration. The problem is particularly acute during rotor deceleration after the materials have been centrifuged since any vibration occurring during deceleration may disturb or agitate the particles that have been centrifugally separated and, to varying degrees, put them back into at least partial suspension, thereby impairing the result of the experiment or test.
SUMMARY OF THE INVENTION The invention herein constitutes an improvement over prior art centrifuges having vibration preventing or compensating means. The present invention comprises a novel centrifuge drive system comprising a compound articulated mounting system for the rotor and for the rotor drive shaft. The new system comprises a motor driven drive shaft and a rotor drive shaft pivotally articulated upon one end of said drive shaft, a universal joint upon which the rotor is mounted, and a slide block integrated with said universal joint and mounted on the motor driven drive shaft. Said slide block is movable laterally to accommodate the movement of the geometric center of the spinning rotor to a position where its center of gravity becomes aligned with the axis of the centrifuge drive system and remains there during high speed centrifugation and deceleration through critical speeds until the rotor comes to a stop.
A novel feature of the invention is the provision of an articulated rotor shaft which notonly transmits rotational energy from the drive system of the centrifuge to the rotor, but also permits the lateral movement of the rotor whereby the geometric center thereof may be displaced so that its center of gravity becomes dynamically aligned with the axis of the drive system.
Another feature of the invention is the provision of a sliding block element integrated with a universal ball joint mounting of the rotor, said slide block being captive at the top of the centrifuge drive shaft. Said slide block is engaged by resilient damping friction means for controlling the lateral movement of said block relative to the centrifuge drive shaft when accommodating for the movement of the center of gravity of the rotor into alignment with the rotational axis of the centrifuge drive shaft. Said damping means assists in maintaining the stability of the drive system once it has achieved dynamic balance.
The centrifuge herein incorporates similar resilient bottom mountings for the centrifuge drive shaft and for the drive shaft housing, as disclosed in U. S. Pat. No. 2,827,229. The resilient mounting at the bottom of the system is stronger than the initial friction of the sliding block provided by a ripple washer bearing thereon.
Thus, the centrifuge drive shaft and its bearing assembly as well as the rotor assembly including the sliding block, have a tendency to establish an axial center by virtue of their own weights and of the resilient mounting at the bottom of the system. During acceleration, the spinning rotor gradually finds its own center of gravity by virtue of the lateral movement of the sliding block relative to the established rotational axis of the drive system. After the spinning rotor has found its center of gravity which becomes axially aligned with the drive system, it remains in that position throughout the higher speeds of acceleration and throughout centrifuging speed and during the lowering speeds of deceleration until the rotor stops.
Centrifugal levers may also-be provided for extra security in automatically locking the slide block in a fixed position during high speed centrifuging rotation of the rotor, and for automatically releasing the slide block during deceleration of the rotor. Thus, during said critical speed phase, the slide block is free to move to permit corresponding dynamic free gradual movement of the geometric center of the rotor to shifting positions relative to the rotational axis of the centrifuge drive system whereby vibration of the rotor and of the rotor mount assembly and of the rotor shaft assembly are prevented. A universal joint mounting is also provided for the rotor so that the latter maintains its horizontal center of gravity plane in position during the centrifuging procedure.
It is understood that the principles of operation and the structural arrangements disclosed and claimed herein are applicable to the complete spectrum from low speed to ultrahigh speed centrifugation, with the requisite adaptations as permitted and made possible by the present invention.
These and other novel features and advantages of the present invention will be described and defined in the following specification and claims.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an elevation of the centrifuge of the present invention, partly broken away and partly in section, showing mainly the exterior of the rotor and the exterior of the rotor mounting hub and of the drive assembly, as well as a fragmentary portion of the support frame of the apparatus, some parts being omitted;
FIG. 2 is an enlarged vertical central section view of the apparatus shown in FIG. 1, omitting the rotor, some parts being shown in elevation and some parts being shown in dotted outline, said Figure illustrating the positions of the respective parts when the drive shaft and the rotor shaft are axially aligned.
FIG. 3 is a still further enlarged plan view of insert elements at the top and bottom of the pivoting rotor drive shaft shown in FIG. 2;
FIG. 4 is a view taken on line 44 of FIG. 2, some parts being omitted;
FIG. 5 is a greatly enlarged view, similar to FIG. 2, showing the location of the rotor hub and the pvioting action of the rotor drive shaft when the geometric center of the spinning rotor has moved to a position where the center of gravity of the rotor is axially aligned with the axis of the drive shaft;
FIG. 6 is an enlarged perspective view of one of two ripple spring washers located in the centrifuge assembly; and
FIG. 7 is a greatly enlarged perspective view of the pivoting rotor drive shaft.
Where cross-section views are illustrated, it is to be understood that most of the component parts are intended to be circular in shape, except where described as being non-circular in shape.
DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to the drawings in detail, the apparatus herein comprises a motor or power shaft 11, the lower end of which is connected to an electric motor or the like, not shown, and which is used to power the apparatus. Alternatively, power shaft 11 may be rotatcd by means other than an electric motor, namely, by a pulley drive, turbine drive, gear drive, or the like.
The apparatus herein is mounted on a frame 12, a fragmentary portion of which is shown in FIG. 1, and which may comprise a circular ring mounted upon a plurality of downwardly extending legs in circular array in a manner comparable to that shown in Blum, U. S. Pat. No. 2,827,229, said frame and legs also supporting the electric motor or the like.
Secured to frame 12 is a circular mounting ring 13 by means of a plurality of spaced bolts 14. A tubular bearing housing 16 is located centrally and extends upwardly of mounting ring 13. Formed integrally at a short distance from the lower end of bearing housing 16 is an annular flange 17. See FIG. 2. Spaced downwardly from flange 17 near the lower end of bearing housing 16, is a removable ring 18 which is secured in position by means of a lock washer l9 fitting into a suitable annular recess near the lower end of housing 16.
The outside diameters of flange 17 and of ring 18 are substantially the same. Located between flange 17 and ring 13 is an annular resilient mounting cushion 21 made of rubber or the like. Mounting cushion 21 has an annular recess intermediate its upper and lower surfaces which accommodates with a snug fit the inner annular portion of mounting ring 13 whereby the lower end of bearing housing 16 is resiliently coupled thereto. The removability of lock washer 19 and of ring 18 permits the removal of annular cushion 21 from the lower end of housing 16 so that the apparatus can be disassembled and subsequently re-assembled with these replaceable parts.
Connected by means of set screw 23 to the upper end of motor shaft 11 is a circular coupling housing 24, the upper portion of which is integrally formed in an upwardly extending tubular coupling collar 26. The outside diameter of coupling housing 24 and of tubular coupling collar 26 is somewhat smaller than the inside diameter of stationary bearing housing 16 whereby the former rotate freely within the lower end portion of the latter.
Located within tubular coupling collar 26 is a resilient coupling ring 27 made of rubber or the like, said coupling ring being either uniform in annular crosssection or being lobed to form a plurality of radially spaced apart elements for enhanced resiliency. Mounted fast within central aperture of ring 27 is a metallic adapter element 28 which, in turn, has a central square aperture which removably accommodates with a close sliding fit the square-shaped stub 31 of a bearing drive shaft 32 which extends axially upwardly through housing 16. The lower end of stub 31 is spaced apart from the upper end of motor shaft 11. Resilient coupling ring 27 and adapter element 28 are enclosed and retained within housing collar 26 by means of cap 33 secured by means of an integrally formed downwardly extending collar on said housing with a press fit. Cap 33 has a top, central aperture through which stub 31 freely extends. The rotation of power shaft 1 1 causes the rotation of drive shaft 32 by way of coupling 24, couping ring 27, and adapter element 28. The resilient mounting formed by cushion 21 is approximately in the same plane as the resilient coupling formed by ring 27 between motor shaft 11 and drive shaft 31.
Mounted within bearing housing 16 are upper and lower spaced apart bearings 34, the inner races of which surround drive shaft 32 and the outer races of which abut the inner wall of housing 16. Bearings 34 are maintained in their spaced apart relationship by means of spacer sleeve 36 surrounding shaft 32, while said bearings are maintained in position within housing 16 by means of tru-arc rings 37, or the like.
The upper end of drive shaft 32 terminates in an integrally formed circular crown 41 of enlarged diameter, said crown extending above and spaced apart from bearing housing 16. integrally formed at the upper portion of crown 41 is an upwardly extending annular skirt 42 defining a slide block chamber 43. See FIG. 5. Threadably connected to crown 41 and enclosing skirt 42 is a circular clamp ring 44, the upper end of said ring having an integrally formed and inwardly extending annular flange 45.
Located axially in the top of crown 41 is an annular recess 46 in which is secured fast an annular insert 47 made of bronze or steel and having a square-shaped central aperture 48. (See FIGS. 2, 3 and 5) Aperture 48 pivotally accommodates the lower square ball end 51 of rotor drive shaft 52, the upper end of which terminates in a square ball end 53 similar to ball end 51.
Positioned on the top surface of crown 41 and rotating therewith is a support ring 54 made of hardened metal or the like, and upon which rests a ball thrust bearing 56. Movably resting upon thrust bearing 56 is an annular slide block 57, said block being movable in all directions in a horizontal plane on said bearing 56 relative to the axis of shaft 32 and crown 41. Positioned on the top surface of slide block 57 is an annular friction ring 58, on top of which is located an annular ripple spring washer or pressure spring 59. The dimension between the floor of chamber 43 and the bottom surface of flange 45 is such that said captive ripple spring washer 59 exerts just sufficient downward pressure upon sliding block 57 to prevent undue free movement of the latter without preventing suitable and necessary movement of said block in all lateral directions in its function of accommodating and responding to centrifugal forces, as will be explained hereinafter.
In some embodiments of the invention, clamp ring 44 may optionally be provided with a plurality of radially spaced apart vertical slots 61 within each of which are freely pivotally movable centrifugal locking levers 62 mounted on pins 63 at the upper portion of said clamp ring. See also FIG. 4. The upper portion of each centrifugal lock lever 62 has an inwardly and downwardly extending finger 64 which, when the apparatus is spinning at certain predetermined speeds, bears down upon friction ring 58 to cause the latter to lock sliding block 57 into an immovable position. The weight ofall of the locking levers 62 is determined by empirical or computer means to respond at a particular rate of rotation of the spinning apparatus for causing fingers 64 simultaneously to lock sliding block 57 in a fixed position. This locking action takes place when a predetermined speed of rotation, which is after the critical speed, is achieved during acceleration of the centrifuge. Said centrifugal locking levers 62 release sliding block 57 during deceleration of the centrifuge at a predetermined speed. Accordingly, centrifugal locking levers 62 cause sliding block 57 to be locked in position only above a certain predetermined centrifuging speed. Below such predetermined speed, the sliding block 57 is free to move horizontally in respect of the geometric axis of the centrifuge apparatus for reasons that will be explained hereinafter.
The centrifuge rotor 71 of the apparatus is mounted by means of a bolt 72 or the like to a rotor hub 73 shaped in this embodiment in the form of a truncated cone. Hub 73 has an axial recess 74 in which is firmly secured an annular insert 76, similar to annular insert 47 (FIG. 3), the central square aperture 76A of which pivotally accommodates square ball end 53. A somewhat larger adjacent axial recess 77 in hub 73 accommodates an annular bearing block 78, the interior of which has a pair of adjacent annular bearing surfaces '79 and 81 positioned at an angle relative to each other. Bearing block 78 is retained in position within recess 77 by means of the upper circular edge of annular clamp ring 82 threadably inserted in the central aperture of hub 73 and secured in position by means of set screw 33 extending laterally through the wall of hub 73. The bottom portion of clamp ring 82 has an integrally formed, inwardly extending annular flange 84 upon which rests a ripple spring washer or pressure spring 86 which, in turn, supports annular friction ring 87.
The central aperture of friction ring 87 is shaped in the form of a curved annular seat 88 which is slidably engaged by a universal hollow ball joint 89 which also slidably engages annular surfaces 79 and 81 of block 78. Thus, rotor hub 73 is pivotably movable relative to universal ball joint 89 by virtue of the sliding engagement between block 78 and ball joint 89. Spring ripple washer 86 has sufficient biasing action between flange 84 and ring 87 to cause friction ring 87 to exert the requisite amount of pressure against ball joint 89 to provide the requisite frictional engagement between said ball joint and block 78 in order to prevent undue excessive pivoting action between hub 73 and said ball joint while, at the same time, said spring is sufficiently yieldable to permit the necessary adjustment pivoting action that takes place to a limited degree while rotor 71 is spinning under various centrifuging conditions.
At the bottom of ball joint 89 is an integrally formed, downwardly extending sleeve 91 whose external annular sloping surface mates with the internal annular sloping surface of an upwardly extending collar 92 formed integrally with slide block 57. The lower end of sleeve 91 extends below slide block 57 and threadably accommodates a nut 93 which secures sleeve 91 firmly into collar 92. Thus, the universal hollow ball 89 and block 57 form an integrated unit whereby any lateral movement of ball joint 89 in any horizontal direction is accompanied by a corresponding movement of collar 92 and slide block 57.
Ball joint 89 and sleeve 91 have a common axial aperture 94 within which rotor drive shaft 52 freely extends and within which said shaft is pivotally movable without touching any portion of ball joint 89 or sleeve 91. Since rotor shaft 52 is pivotally articulated on the upper end portion of drive shaft 32, and rotor 71 is pivotally articulated at universal ball joint 89, said rotor is given the freedom of movement of its geometric center away from the axis of the drive system comprising drive shaft 32 in order to permit the center of gravity of said rotor to become aligned with the drive system axis.
OPERATION When the centrifuge rotor 71 is mounted on hub 73 at the beginning of a centrifuging run, said hub and rotor are normally axially aligned with bearing housing 16 as shown in FIGS. 1 and 2. After the materials to be centrifuged are inserted in the radially arrayed sloping receptacles, not shown, of rotor 71, with care exercised to distribute the weight of said materials uniformly around the axis thereof, the motor, not shown, is started in order to rotate the motor shaft 11 which, by way of the resilient coupling described hereinbefore, causes the rotation of drive shaft 31 within bearings 34. The rotation of the square aperture of insert 47 engaging lower square ball end 51 of rotor drive shaft 52 causes the latter to rotate in unison therewith while the engagement of upper square ball end 53 of said shaft with the square aperture of insert 76 causes the corresponding rotation of hub 73 and of rotor 71.
If rotor 71, with its contents in place, is perfectly balanced symmetrically and axially around drive shaft 52, said rotor will remain axially aligned as it accelerates in speed as well as during full speed centrifugation and deceleration to a complete stop. This condition would be achieved because the center of gravity of the rotor would coincide with its geometric center.
Absolutely perfect symmetrically balanced conditions are rarely achieved since the center of gravity of the spinning rotor usually does not coincide with its geometric center, as a result of which the rotor and the rotor drive system are caused to vibrate.
If the drive system for the centrifuge, including the bearing housing and rotor hub were rigidly interconnected axially, the vibration caused by a spinning rotor whose center of gravity is spaced apart from its geometric center would subject the complete drive and support system for the rotor to undue damaging stresses as well as cause the possible fracture thereof and destruction of the centrifuge.
At start-up of centrifugation, when the rotor is loaded with materials to be centrifuged, the support structure for the rotor and all of its component parts are substantially axially aligned as shown in FIG. 2. At that time, the bottom surfaces of respective fingers 64 are slightly spaced apart from the top surface of friction ring 58 by virtue of the effect of gravity upon levers 62. After start-up of centrifugation and as rotor 71 accelerates rotationally, any imbalance of said rotor, due to less than perfect balance or to uneven distribution of materials to be centrifuged, or both, causes the geometric center of said rotor to depart from the axial center of the support structure of the apparatus. This departure of the geometric center of rotor 71 and rotor hub 73 from the axial center of the drive system including drive shaft 32 and bearing housing 16 is permitted by the sliding action of the block 57 between bearing 56 and friction ring 58 as well as by the pivoting action of rotor shaft 52, as shown in FIG. 5. By this action, the combined center of gravity of rotor 71 and hub 73 is brought into alignment with the axial center of the drive system comprising drive shaft 32 and crown 41. The extent of the angular deviation of rotor shaft 52 from the axial center of the drive system is determined by the extent to which the geometric center of the rotor deviates from its center of gravity. See FIG. 5. When said center of gravity becomes dynamically aligned with the axial center of the drive system, the rotor continues to spin substantially without any vibration notwithstanding that its geometric center is displaced from the axis of the drive system. Furthermore, rotor 71, acting gyroscopically, remains substantially horizontal during high speed spinning by virtue of the frictionally resistant sliding engagement of the surface of ball joint 89 with annular surfaces 79 and 81 of block 78, as well as with annular seat 88, of friction ring 87.
During the foregoing action, slide block 57 also becomes axially displaced from the axial center of the drive system in accordance with the extent to which the geometric centers of rotor 71 and of rotor hub 73 becomes displaced from said drive system axial center. Slide block 57 is free to shift its position in order to accommodate to the departure of the geometric center of rotor 71 from the axial center of the drive system, but said sliding action is controlled to prevent erratic action thereof by a modicum of frictional pressure applied to block 57 by means of friction ring 58 being urged downwardly upon block 57 by means of yieldable spring washer 59. While spring washer 59 exerts a modicum of pressure, it is sufficiently yieldable to permit the gradual adjusting movement of slide block 57 to the adjusting deviation of the geometric center of rotor 71 from the axial center of the drive system after the rotor has accelerated through the critical speeds.
Although pivoting lock levers 62 may be dispensed with in some embodiments, they may nevertheless be found useful for locking slide block 57 in a particular location after rotor 71 has achieved a predetermined speed upon acceleration as, for example, to resist any shock tending to disrupt dynamic rotation. Accordingly, the size and weights of levers 62 may be determined as to be operative by centrifugal forces whereby their outward movement causes fingers 64 to bear downwardly upon friction ring 58 with sufficient force to lock slide block 57 securely between said friction fring and bearing 56.
Upon deceleration of rotor 71, when centrifugal force is reduced, the lower portions of lock levers 62 move inwardly to cause their respective fingers 64 to become spaced apart from friction ring 58 whereby slide block 57 is again permitted to move in accordance with the movement of rotor 71 in respect of the axial center of the drive system.
The operation of the centrifugal locking system comprising levers 62 is limited to centrifuging speeds above the critical range of speeds in the course of which the center of gravity of rotor 71 becomes aligned with the axial center of the drive system comprising drive shaft 32. During the critical range of speeds in which the spinning rotor 71 adjusts itself to the axial center of the drive system due to possible imbalances of the rotor or of its contents, or both, it is important to provide freedom of movement for slide block 57 in any horizontal direction so that rotor shaft 52 may move pivotally and permit the geometric center of rotor 71 and of hub 73 to move in any necessary horizontal direction for said adjustment function. The movement of the geometric center of rotor 71 in a horizontal plane along with the similar horizontal movement of slide block 57 is made possible by the fact that the square ball end 53 of rotor shaft 58 is capable of sufficient vertical movement with aperture 76A of insert 76 to permit the aforementioned horizontal movement of the rotor and the slide block while, at the same time, rotor shaft 58 performs the function of receiving rotational power from drive shaft 32 and transmitting it to rotor hub 73 and rotor 71. Thus, ball end 53 moves in an arcuate path while the center of gravity of rotor 71 moves in a horizontai plane. By providing square ball ends for rotor shaft 58 which are freely pivotable in all directions within the respective square apertures in inserts 47 and 76, mechanical expedients for securing the ends of the rotor shaft by physical means to their respective seating elements are obviated.
It is understood that the inside diameter of clamp ring 44 will be of sufficient magnitude to permit the lateral movement of slide block 57 in any horizontal direction to the extent that may be expected or required in accommodating for deviation of the center of gravity of rotor 71 from the axial center of the centrifuge drive system. The relative dimensions of the various component parts may be determined by suitable empirical means.
In the absence of the adjustment mechanism herein comprising slide block 57, rotor shaft 52, and universal ball joint 89, rotor 71 would vibrate during acceleration and deceleration during the aforementioned critical range of speeds, as is characteristic of centrifuge operation. Although vibration during the critical range of speeds during acceleration may be tolerated for the reason that the materials in the centrifuge have not as yet been subjected to centrifuging action, it is most important that vibration be eliminated during deceleration in order to prevent any agitation of the centrifuged materials in the rotor that would otherwise impair the integrity of said materials and possibly destroy the experiment or test intended to be made by the centrifugation process. Accordingly, it is critically important that vibration of the rotor be prevented, especially during deceleration, so that the rotor spins smoothly throughout the deceleration process until it comes to a stop. Therefore, when deceleration starts, the slowing down of the rotor permits the retraction of centrifugal levers 62 above the critical range of speeds after which slide block 57 is freed.
It is understood that the word rotor as used in the specification and claims herein, may subsume the combination of hub 73 and rotor 71.
Although the present invention has been described with reference to particular embodiments and examples, it will be apparent to those skilled in the art that variations and modifications can be substituted therefor without departing from the principles and true spirit of the invention. The Abstract given above is for the convenience of technical searchers and is not to be used for interpreting the scope of the invention or claims.
1. A centrifuge comprising a frame, a drive shaft on said frame, a rotor shaft, one end of said rotor shaft being pivotally connected to an end portion of said drive shaft and rotated thereby, a rotor operably and pivotally connected to the other end of said rotor shaft, an articulating connection between said rotor and said drive shaft, said articulating connection being movable perpendicularly relative to the axis of said drive shaft when said rotor shaft moves pivotally relative to said drive shaft, and a hub in said rotor being connected by a universal mounting on said articulating connection.
2. A centrifuge according to claim 1 wherein said articulating connection comprises a tubular member surrounding and spaced apart from said rotor shaft, the upper end portion of said member forming a ball joint with the interior of said hub, and an outwardly extending annular, slide slide block at the other end portion of said member, said block being slidably engaged at the upper end of said first shaft for movement in all lateral directions relative to the axis of said first shaft.
3. A centrifuge according to claim 2 and further comprising first means on said drive shaft applying limited frictional engagement upon said slide block while permitting lateral movement thereof, and second means on said drive shaft operating by centrifugal force when said shaft achieves a predetermined minimum speed of rotation to engage said first means to cause the latter to lock said slide block in a fixed position relative to said drive shaft.
4. A centrifuge according to claim 2 wherein said first means comprises a ring resting upon said slide block and said second means comprises a plurality of spaced apart, freely pivotally mounted elements in circular array on the upper portion of said drive shaft, and integrally formed fingers on said elements which, when said drive shaft reaches a predetermined minimum speed of rotation, exert pressure upon said ring to cause the latter to lock said slide block into a fixed position relative to said drive shaft.
5. A centrifuge according to claim 2 and further comprising an annular thrust bearing on said drive shaft, said slide block being movable slidably on said bearing.
6. A centrifuge according to claim 2 and further comprising an annular friction ring, said friction ring bearing against and securing said ball joint pivotally within said rotor hub.
7. A centrifuge according to claim 4 and further comprising an annular resilient spring washer located between said fingers and said ring.
8. A centrifuge according to claim 6 and further comprising an annular resilient washer adjacent saidfriction ring, said washer imparting limited yieldability to said friction ring.
9. A centrifuge according to claim 1 and further comprising a source of rotating power mounted on said frame, and a resilient connection between said source and said drive shaft.
10. A centrifuge according to claim 9 and further comprising a bearing housing surrounding said drive shaft, and a second resilient connection between said bearing housingand said frame, said first mentioned resilient connection and said second resilient connection being positioned approximately in the same plane.
11. A centrifuge comprising a frame, a bearing housing mounted on and extending upwardly from said frame, a rotatable drive shaft within said housing, a rotor shaft, the lower end of said rotor shaft being pivotally connected to the upper end of and rotated by said drive shaft, a rotor operatively pivotally connected to the upper end of said rotor shaft and rotated thereby, a tubular sleeve located coaxially around and spaced apart from said rotor shaft, the upper portion of said sleeve forming a universal joint with the interior of said rotor, a radially extending annular slide block mounted on the lower portion of said sleeve, said slide block being slidably mounted and held captive at the top portion of said drive shaft and being movable laterally in all radial directions to permit the pivoting action of said rotor drive shaft.
12. A centrifuge according to claim 11 and further comprising a thrust bearing upon which said block rests and is movable, and a spring biased friction ring on top of said block for applying limited frictional resistance to the movement of said block.
13. A centrifuge according to claim 12 and further comprising a plurality of radially spaced apart levers on said shaft, said levers being subjected to centrifugal forces which are operative at a predetermined range of speeds to urge said friction ring against said block to lock the latter in fixed position.
14. A centrifuge according to claim 11 wherein the respective ends of said rotor shaft are formed as square balls, and further comprising a square aperture in the top of said drive shaft accommodating the lower square ball, and a second square aperture in said rotor accommodating the upper square ball, said square balls being pivotable within their respective square apertures and rotated thereby, the rotation of said drive shaft causing the rotation of said rotor by way of said rotor shaft.
15. A centrifuge according to claim 11 and further comprising a resilient mounting at the bottom of said drive shaft, and a separateresilient mounting at the bottom of said housing.
16. A centrifuge comprising a frame, a rotating drive system on said frame, a rotor, a rotor shaft, one end of said rotor shaft being pivotally connected to and rotated by said drive system, the other end of said rotor shaft being operably pivotally connected to and rotating said rotor, an articulating connection between said drive system and said rotor separate from said rotor I shaft, said connection being operative to bring about movement of the rotor in a horizontal plane and the axial alignment of the center of gravity of the spinning rotor dynamically with the rotational axis of said drive system.
17. A centrifuge according to claim 16 wherein the upper end of said articulating connection is in the form of a ball joint located within said rotor, and the lower end of said articulating connection is in the form of a slide block mounted on said drive system and movable laterally in all directions relative to the axial center of said drive system.
18. A centrifuge according to claim 17 and further comprising a first spring biased element applying limited frictional resistance upon said ball joint, and a second spring biased element applying limited frictional resistance upon said slide block.
19. A centrifuge according to claim 16 wherein said articulating connection surrounds and is spaced apart from said rotor shaft when the latter is axially aligned with and when it is pivotally angled relative to said drive system.
20. A centrifuge according to claim 17 and further comprising at least one centrifugal element on said drive system, said element being operative within a predetermined range of rotational speeds of said rotor to lock said slide block in a fixed position.
21. A centrifuge according to claim 16 in which said drive system comprises a drive shaft and a bearing housing surrounding said drive shaft, said centrifuge further comprising rotational power means on said frame for rotating said drive shaft, a resilient coupling between said drive shaft and said power means, and a second independent resilient mounting between said housing and said frame.
22. A centrifuge comprising a frame, a rotatable drive shaft on said frame, a rotor, a rotor shaft, one end portion of said rotor shaft being pivotally connected to said drive shaft and rotated thereby, the other end portion of said rotor shaft being operably pivotally connected to said rotor, and an articulating connection means between said rotor and said drive shaft, said articulating connection means being movable in a horizontal plane relative to the vertical axis of said drive shaft when said rotor shaft moves pivotally and the center of gravity of the spinning rotor moves in a horizontal plane to become aligned with the axis of rotation of said drive shaft.
23. A centrifuge according to claim 22 said articulating connection means comprising an articulating connection (5731) between said rotor and said drive shaft, a first universal yieldable friction mounting (86,87) between said articulating connection and said rotor, and a second yieldable friction mounting (59) between said articulating connection and said drive shaft, said second yieldable friction mounting being movable horizontally in all directions relative to said drive shaft.
24. A centrifuge according to claim 23 and further comprising a plurality of pivotable levers on said drive shaft, said levers being operated by centrifugal force for clamping said second yieldable frictional mounting securely to said drive shaft during a predetermined range of speeds of rotation of said drive shaft and said rotor.
25. A centrifuge according to claim 22 wherein the pivotal connection between the rotor shaft and the rotor comprises a square shaped recess in said rotor and a square ball end on said rotor shaft accommodated by said recess and movable pivotably in all directions relative thereto, said square ball end moving in an arcuate path during the movement of said rotor in a horizontal plane.
26. A centrifuge according to claim 22 wherein said articulating connection comprises an annular slide block surrounding and spaced apart from said rotor shaft and mounted for horizontal movement on said drive shaft, a ball joint in said rotor surrounding and spaced apart from said rotor shaft, a tubular connection between said ball joint and said slide block, said rotor and said slide block being movable in a horizontal plane only relative to said drive shaft while said rotor shaft moves pivotally between said drive shaft and said rotor.
27. A centrifuge according to claim 26 and further comprising a yieldable friction element mounted between said slide block and said shaft.
28. A centrifuge according to claim 26 and further comprising a plurality of pivotable levers on said drive shaft, said levers being operated by centrifugal force for clamping said slide block securely to said drive shaft during a predetermined range of speeds of rotation of said drive shaft and of said rotor.
29. A centrifuge comprising a frame, a vertical rotatable drive shaft on said frame, a rotor shaft, a pivot connection between said rotor shaft and said drive shaft, a pivot connection between said rotor shaft and said rotor, means connected between said rotor and said drive shaft and movable in a horizontal plane relative to said drive shaft and means on the pivot connection between the rotor shaft and the rotor within which the end of said rotor shaft moves in an arcuate path when the rotor moves in a horizontal plane.
30. A centrifuge comprising a frame, a rotatable drive shaft on said frame, a rotor mounted on said drive shaft and movable in all directions restricted in a perpendicular plane relative to the axis of said drive shaft, and a rotor shaft, one end of said rotor shaft being pivotally connected to said drive shaft, the other end of said rotor shaft pivotally engaging the interior of said rotor, said other end of said rotor shaft moving in an arcuate path when said rotor moves in said perpendicular plane.
31. A centrifuge according to claim 30 and further comprising a square ball end formed on said other end of the rotor shaft and a square recess in said rotor engaged by said square ball end.