Centrifuge

Abstract

A centrifuge for serum/plasma separator tubes in which racks holding one or more tubes can be inserted into slots in the rotatable member of the centrifuge. The slots of the rotatable member are positioned to provide dynamic balancing when all the slots are filled with racks of tubes. When the slots are not all filled with racks of tubes, the centrifuge is so designed that such racks can be positioned opposite each other to maintain such balance. In a modified form, the entire rotatable member loaded with racks of tubes can be loaded onto or removed from the centrifuge as a unit, thereby providing a quick, convenient and simple way of handling a full load of tubes at one time.

Description

BACKGROUND OF THE INVENTION

The prior art includes the following pertinent U.S. Pat. Nos. 3,674,198 3,151,073 3,643,812 3,142,385 3,474,913 3,050,239 3,454,217 2,755,018 3,339,837 2,560,988 3,289,927 486,390

None of these patents show or describe a centrifuge head embodying the means, hereinafter described and claimed, for mounting a plurality of racks holding a plurality of separator tubes on the periphery of the head and for holding such racks on the head during rotation of the head. Furthermore, such patents do not disclose the specific design of the racks for holding the plurality of tubes.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a centrifuge for separator tubes designed to hold a plurality of racks or tubes on the periphery of a rotatable member, which racks can be positioned on the said member to maintain dynamic balance during rotation of the centrifuge.

It is a further object to provide racks for the centrifuge which will hold a plurality of tubes and are so designed that they can be fitted into support means on the periphery of the rotatable member of the centrifuge.

It is a further object to provide means on the centrifuge for holding the racks and tubes so that they cannot leave the support means during centrifugation.

It is a further object to provide a centrifuge with a removable rotatable member which will hold racks of tubes so that all the racks and tubes supported on the rotatable member can be removed as a unit to facilitate loading and unloading of the centrifuge.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages will become apparent from the following description which is to be taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a perspective view, partly broken away, of the centrifuge of the present invention;

FIG. 2 is a side elevation, partly in section, showing the centrifuge with one rack of tubes in place on one side and the rack on the opposite side removed;

FIG. 3 is a top plan view of a portion of the centrifuge showing how the racks of tubes are inserted downwardly into the top of the centrifuge;

FIG. 4 is a perspective view of the rack of tubes which is inserted into the centrifuge;

FIG. 5 is a side elevation, partly in section, of the tube rack containing six tubes;

FIG. 6 is a view, partly in section, along the line 6--6 of FIG. 5;

FIG. 7 is a top plan view of the tube rack;

FIG. 8 is a perspective view, partly broken away, of a carrier for holding a plurality of tube racks; and

FIG. 9 is a perspective view of a modified form of centrifuge in which the entire rotatable member holding the tube racks can be removed as a unit.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIGS. 4-7, serum/plasma separator tubes 10, provided with top and bottom stoppers 10a and 10b respectively, are shown resting in a rack 11. This rack may be formed of a strong non-corrodable material, for example stainless steel, It consists of a bottom 12, side members 13--13 and flanges 14--14. The opposite side members 13 are spaced to provide adequate clearance for the tubes. The rack, as shown, is of a size to hold six tubes, but it will be understood that such size may be varied to hold more or fewer tubes. A flat plate 15, preferably also made of stainless steel, extends across the top surfaces of the flanges 14 and is rigidly secured to them by any suitable means, for example by welding. The top plate 15 is provided with a plurality of holes 16 to receive the tubes 10 and keep them uniformly spaced from each other. These holes are of a size that they will provide sufficient clearance to receive the lower stoppers of the tubes 10. Secured to the bottom 12 of the rack is a spacer guide 17 having a plurality of holes 18 corresponding in number to the holes 16 in the top plate 15. The holes 16 and 18 are aligned so that the tubes inserted into the top plate 15 and the spacer guide 17 will keep the tubes parallel and uniformly spaced.

Referring to FIG. 2, there is a motor housing 19 from which extends the motor shaft 20. The motor enclosed within the housing is of a conventional type for driving a centrifuge and is not illustrated or described. A rotatable member 21 fits onto the motor shaft 20, being vertically supported by the snap ring 22 or some other suitable means. The rotatable member 21 has an even numbered plurality of uniformly spaced cutouts 21a around the periphery (FIG. 3). On each side of each cutout is a guide slot 23 (FIGS. 2 and 3) to receive each tube rack. The lower ends of the guide slot 23 are closed by the circular ring member 24 which is secured to the rotatable member 21 by screws 25 or other suitable means. The circular ring member 24 also acts as a stiffening and restraining member resisting the outward thrust of centrifugal force on the lower portions of the rotatable member 21.

Further referring to FIG. 2, there is shown a rack 11 of six tubes 10, rotated 90.degree. from the vertical position shown in FIG. 4 and inserted into the rotatable member 21. The flanges 14 (FIG. 4) and the ends of the top plate 15 fit into the mating slots 23 (FIG. 2) of the rotatable member. The rack is lowered into the rotatable member until it comes to rest against the circular ring member 24.

The vertical height of the spacer guide 17 is made to cooperate with the central rotatable member 21 and the motor housing 19 so that, during loading of a tube rack, if an individual tube is jostled radially inward until the top stopper contacts the motor housing 19, part of the tube's lower stopper is still within its hole in the guide 17. Then when the centrifuge motor starts to rotate, the displaced tube will be thrust radially outward by centrifugal force and will automatically reposition itself in the proper location.

After the tube racks 11 (FIG. 1) are positioned in the slots of the rotatable member a cover 26 is placed on top of the rotatable member closing the upper ends of guide slots 23. Both the cover member 26 and the rotatable member 21 are secured to the motor shaft 20 by screwing the knurled and slotted knob 27 into the top of the shaft (FIG. 2).

The motor housing 19 (FIG. 2) rests on a base plate 28 from which projects upwardly a shell 29 which serves as a protective shroud around the centrifuge.

When all eight tube racks with their 48 tubes are loaded into the centrifuge as heretofore described and the cover 26 is secured with the knob 27, the centrifuge is spun at the speeds and time intervals desired (which may be automatically programmed) so that the different liquids and/or solids are separated in all the tubes. Then the centrifuge is stopped and the racks of tubes are unloaded and placed in a tube rack carrier 30 (FIG. 8) for transfer to the location where tests are to be performed or the different elements are to be analyzed or handled.

The apparatus has great flexibility for centrifuging fewer tubes than a full load of 48 tubes. Any pairs of racks may be omitted as long as the empty regions are ones symmetrically across a diameter of the centrifuge, so that dynamic balancing will be preserved. Also two opposite racks having less than six tubes can be used as long as the same number of tubes are in each and they are in the same respective locations in each rack to maintain dynamic balancing. If the number of blood-filled tubes on hand to be centrifuged is an uneven number, an additional tube can be filled with water to provide a matching weight and this tube can be used with the others to provide an even number of tubes in total, for handling as described above. Thus, the apparatus and method of the present invention has complete flexibility in being able to centrifuge any number of tubes at one time, from one up to a maximum of 48 tubes.

Referring to FIG. 8, the tube rack carrier 30 has a base 31, end members 32 and a top 33. The top 33 has a plurality of cutouts 34 spaced from each other and each sized to receive a tube rack. Secured to the base 31 are a pair of spaced, parallel guide members 35 which run the length of the base. Extending vertically from these members 35 are tabs 36 with beveled corners. These tabs are located to guide the tube racks 11 into the correct positions as they are inserted into cutouts 34 and lowered to the bottom of the carrier. When a tube rack is being lowered through the cutout 34 it can only be rocked right or left. If it comes to rest on top of a tab 36, the top of the tube rack will be so much higher than normal and higher than other tube racks that it will be immediately noticeable and the operator will then shift it to its proper position.

The above description has covered the loading and unloading of the centrifuge by the insertion or removal of the tube racks individually. In such case the rotatable member 21 has remained affixed to the centrifuge. As an alternative, the entire rotatable member 21 loaded with tube racks and tubes can be removed from the centrifuge and replaced with another pre-load rotatable member, so that the second load can be centrifuged while the first load is being removed from the first rotatable member and replaced with a third set of serum separators. The removal of the entire rotatable member and its load can be accomplished by providing for the insertion of a pair of handles into the member by which the member can be lifted from the centrifuge, as shown in FIG. 9. The top of the rotatable member is provided with a pair of drilled tapped holes 37 (FIGS. 2 and 3), one on each side of the member. A T-shaped handle 38 (FIG. 9), having a threaded portion and a collar or boss 38a, which limits how far the handle can be screwed into the hole 37 (FIG. 2), is used to lift the member 21 (FIGS. 2 and 9) on each side. The knob 27 (FIG. 2) and the cover 26 are first removed, and handles 38 (FIG. 9) are screwed into the holes 37 (FIG. 2) and the entire rotatable member 21 (FIG. 9) with its load is removed from the centrifuge. It is not necessary for the handles to be screwed so that the bosses 38a are tight against the rotatable member. It is only necessary for the handles to be screwed in sufficiently to prevent the handles from becoming detached from the member. The handles can be oriented so that the cross members are approximately parallel. One handle can then be grasped in each hand with two fingers and the entire rotatable member lifted from the centrifuge and placed on an adjacent work table for loading and reloading. After is has been reloaded it is reinstalled on the motor shaft by reversing the steps described above.

The centrifuge of the present invention has been described and illustrated in connection with serum/plasma separator tubes used in the separation of blood into its light and heavy phases. However, it will be understood that the centrifuge can also be used for the separation of other liquids into their various phases.

It will be obvious to those skilled in the art that various modifications may be made to the apparatus hereinbefore described. Such embodiments are considered to be within the scope of the invention. The above invention is not to be limited except as set forth in the following claims.

Claims

Having thus described the invention, what is claimed is:

1. A centrifuge for liquid separator tubes comprising:

drive means,

a rotatable member mounted on the drive means,

said rotatable member having an even numbered plurality of uniformly spaced supports around the periphery of the rotatable member with opposite supports equidistant from the axis of the drive means,

a rack adapted to hold a plurality of separator tubes spaced from each other,

said rack having means to mount the rack in the said supports of the rotatable member in an attitude normal to the said axis, and

means to secure the racks in the supports,

said rack comprising:

a. a pair of vertical side members spaced from each other by a distance greater than the diameter of said separator tubes and having a height less than the height of said separator tubes;

b. a base member connecting the said side members and adapted to support the separator tubes during loading, unloading and centrifugation;

c. a longitudinal guide member spaced from the base member and supported by the side members and adapted to evenly space the bottoms of the separator tubes; and

d. a top rack member having a series of holes larger than the separator tubes and adapted to space said tubes;

e. said top rack member being secured to bent over edge portions of said vertical side members to form a pair of flanges adapted to fit into cooperating slots in the said supports of the rotatable member and retain the rack in the rotatable member.

2. The centrifuge of claim 1 in which the rotatable member is detachably mounted to the drive means whereby the said member loaded with racks of tubes can be removed from or loaded onto the centrifuge as a unit.

3. The centrifuge of claim 2 which includes handle means detachably secured to the said rotatable member whereby the rotatable member and racks may be lifted in and out of the centrifuge as an assembly.

4. The centrifuge of claim 3 wherein the handle means comprise two handles located along a diameter passing through the axis of said rotatable means and each handle is located equidistant from said axis.

5. The centrifuge of claim 4 wherein the handle means includes a pair of T-shaped portions adapted for comfortable and efficient lifting by the two hands of a user.

6. The centrifuge of claim 5 wherein the T-shaped portion of each handle means is insertable into the rotatable member and includes a boss adapted to limit the distance the handle means can be inserted into the rotatable member.

7. The centrifuge of claim 1 in which each support comprises a cutout in the rotatable member parallel to the axis of the drive means to receive the said rack, and which includes safety closure means detachably mounted to close the upper ends of the said cutouts so that the racks are secured in position while the rotatable member is spinning.